Chazak hu mimenu

Rashi quotes an unbelievable derasha from Chazal that when the meraglim said "chazak hu mimenu" their intention was "kavyachol k'lapei maalah," as if to say the Canaanim were stronger even kavyachol than Hashem and therefore could not be defeated.  To think that the dor dei'ah who witnessed the miracles of yetzias Mitzrayim, kri'as Yam Suf, etc should think that the Canaanim could stand up to G-d defies understanding.

Rav Chaim Hirschensohn has a very clever reading of Rashi that gives it the exact opposite meaning of how it sounds k'peshuto.  The meraglim understood that everything is in G-d's control.  If a nation has power, it's because G- d grants it to them.  When they saw the tremendous might of the Canaanim, the meraglim said "chazak hu" -- this strength is -- "mimenu," something that comes from G-d himself. "Ain Baal habayis yachol l'hotzi misham es keilav," G-d will not withdraw his "kelim," the power and might he has given the Canaanim, for our sake.

Shem mShmuel (see also Meshech Chochma, Netziv at the  beginning of the parsha) writes that the meraglim's plot needs to be seen in context of the nevuah of Eldad and Meidad at the end of last week's parsha that Moshe would die and Yehoshua would be the one leading the nation into Eretz Yisrael.  Moshe was a conduit for the miraculous, but with Yehosha in charge a b'derech ha'teva war would be required.  Recall that when Amalek attacked and Yehoshua led the people in battle, there were no overt miracles -- it was a war, plain and simple.  On the level of derech ha'teva, would people who had sinned in the misonenim episode, who had sinned at kivros ha'taavah, deserve special treatment from G-d?  

Chazal here are not coming to add more criticism on top of the sin of the meraglim, but rather to temper their sin.  The meraglim were truly acting lshem shamayim, as they felt that Hashem himself had enabled  the nations to remain in control of Eretz Yisrael. The meraglim felt that they were unworthy of geulah at this time.  

Rav Hirschensohn ends his piece with a comment no less true today than 100 years ago: "v'zeh yihiyeh mussar l'kol misnagdei hatzionus afilu ha'miskavnim lshem shamayim." Sadly, the lesson still has not penetrated.

Rambam's understanding of ptil techeiles

The Rishonim debate how many strings of techeiles one is required to have in tzitzis.  Rashi and Tos hold there need to be 2 white strings and 2 techeiles strings; Raavad holds that 1 of the 4 strings must be techeiles; Rambam holds 1 of 8.  Rashi and Tos (see Menachos 38 d"h ha'techeiles" base their view on the gemara's derasha on the word "gedilim" being written in plural -- gedil = 2, gedilim= 4. They interpret this to mean not just that 4 strings are required, but that 2 of each variety are required.  Raavad's view is easy to understand -- "ptil techeiles" = 1 ptil, or 1 thread of techeiles.  The hardest position to explain is that of the Rambam.  What is the logic in requiring only 1 of 8 strings -- IOW, half of one fo the 4 whole strings -- to be techeiles?  It is not a gedil, and not even a whole ptil?

The Mishna in Menachos tells us that lavan is not m'akeiv techeiles and techeiles is not m'akev lavan.  The simple pshat in the Mishna is that if you don't have white string you can make tzitzis entirely out of techeiles string; if you don't have techeiles, you can use all white strings.  The Rambam, however, formulates the Mishna's law a little differently (Hil Tzitzis 1:4):

והתכלת אינו מעכב את הלבן והלבן אינו מעכב את התכלת. כיצד הרי שאין לו תכלת עושה לבן לבדו. וכן אם עשה לבן ותכלת ונפסק הלבן ונתמעט עד הכנף ונשאר התכלת לבדו כשר:

When it comes to techeiles not being m'akeiv, the Rambam writes, like we said above, that you can make tzitzis entirely of 4 white strings, but when Rambam quotes the din of lavan not being m'akeiv, he does **not** say you can make tzitzis out of all techeiles string.  What he says is that if you had tzitzis made with white string which then broke so that all that is left is techeiles, the tzitzis are still kosher. 

Why did the Rambam reinterpret the Mishna this way rather than read it k'peshuto?

The answer becomes clear if we look a little earlier in the same perek, to the Rambam's description of how to tie techeiles:

ענף שעושין על כנף הבגד ממין הבגד הוא הנקרא ציצית מפני שהוא דומה לציצית של ראש. שנאמר ויקחני בציצית ראשי. וזה הענף הוא הנקרא לבן מפני שאין אנו מצווין לצובעו. ואין לחוטי הענף מנין מן התורה:
ולוקחין חוט צמר שנצבע כעין הרקיע וכורכין אותו על הענף וחוט זה הוא הנקרא תכלת. ואין למנין הכריכות שכורך חוט זה שיעור מן התורה:

The Rambam in this halacha defines tzitzis as the strings attached to the corner of the garment, and then defines techeiles as the colored string wrapped around those strings.

Implicit in this halacha is a chidush: techeiles is defined not just by its color, but also by its function: it's the string you wrap around the other strings.  The Rambam must have understood that ptil is not a string, but means something wrapped. 
To make tzitzis entirely out of techeiles string would make no sense because by definition techeiles is something wrapped around other strings -- if there are no other strings to wrap around, then your techeiles is not techeiles.  Lavan is not m'akeiv if it is cut off, but it's presence is certainly m'akeiv in order to have something to wrap around.

(Why not wrap techeiles around techeiles?  It seems that techeiles would not fit the Rambam's definition of tzitzis as "min kanaf" as a garment is not usually made entirely out of techeiles.  Korach is next week's parsha -- we're not there yet : )

(See the article by R' Shabtai Rappaport on the ptil techeilet website who spells out this understanding of the Rambam).

Temunas Hashem yabit

What Miriam and Aharon did not appreciate about Moshe Rabeinu is that "temunas Hashem yabit." Netziv explains that Moshe Rabeinu did not see things the way an ordinary person sees things.  There is a way if looking at things that is G-dly, that is special.

I think that is the connection between the parsha of Miriam speaking against Moshe and the parsha of the meraglim. It's not just that both spoke badly.  It's that the meraglim failed to take heed of the fact that there is a way to look at things that goes below surface impressions.  When you look at something holy like Eretz Yisrael you need to put on the glasses of "temunas Hashem yabit" or you may miss the picture completely.

If you don't see the kedushas ha'aretz, the singularity of the land, it is a pgam in your vision, not in the land.

Miriam speaking out

My wife suggested that Miriam speaking out against Moshe separating from Tziporah is consistent with Chazal's portrayal of Miriam being the one who told her father Amram that his separating from Yocheved in Mitzrayim is worse than Phraoah's gezeirah.  (Later found the same idea in Shvilei Pinchas.)

Miriam reached out specifically to Aharon as he was the oheiv shalom v'rodef shalom who was known for restoring shalom bayis. 

Even the best intentions, however, did not immunize Miriam from the danger of lashon ha'ra.  

The grass is always greener

Sivan Rahav Meir quoted a beautiful thought from R Moshe Tzvi Neriah on our parsha: Many people think that if only they lived in some other place, at some other time, had gone to some other school, had a different teacher, different parents, etc then they would be able to excel in their avodas Hashem and their learning.  What do we see from our parsha?  We have the dor de'ah who experienced yetzias Mitzrayim, kri'as Yam Suf, maamad Har Sinai, people who had the zechus of learning Torah directly from Moshe Rabeinu while eating mon and having G-d take care of their every need, and despite all that they complained "mi yaachilanu basar," there's not enough meat in the cholent, and as Rashi explains, that was just an excuse anyway -- in truth, they just wanted out from religion.  They had the best teacher, the best environment, the best of everything, and it did not make a difference.

The environment can't make you into an oveid Hashem or a talmid chacham.  It can only nurture the drive that starts from within.

lock them up

The gemara (Sanhedrin 17) quotes three opinions as to what Eldad and Meided prophesized: 1) that Moshe would die and Yehoshua would lead the people into Eretz Yisrael; 2) that slav birds would come; 3) the future war of Gog and Magog.  The gemara then asks: b'shlama according to the view that they prophesized that Moshe would die, we understand Yehoshua's reaction of "Adoni Moshe kila'eim," lock them up, but according to the other views of what their prophecy was, why did Yehoshua get so agitated?  The gemara answers that Yehoshua held that Eldad and Meided prophesizing in the presence of Moshe was a violation of moreh halacha b'fnei rabbo (see Meg 14b as well and post here) which disrespected Moshe.

Why did the gemara accept Yehoshua's harsh reaction to the prophecy that Moshe would die as justifiable even without the sevara of it being moreh halacha b'fnei rabbo?  If it is a true prophecy, then no matter how uncomfortable the message, Eldad and Meided would have to transmit it and Moshe would have to accept it.  Plenty of nevi'im unfortunately for us were given the job of delivering unpleasant messages to Klal Yisrael.  Why did Yehoshua demand that they be silenced? 

The gemara (Shabbos 30) writes that David haMelech knew that he would die on Shabbos, so every Shabbos he would immerse himself completely in learning so that the malach ha'maves would not be able to overcome him.  R' Zev Hoberman z"l in his sefer Ayeles haShachar writes that if the torah of David could keep the malach ha'maves at bay, kal v'chomer the torah of Moshe Rabeinu.  This is what bothered Yehoshua.  How could the prophecy of Eldad and Meidad be true?  Moshe meis?  Moshe Rabeinu is kulo Torah, his entire being was dedicated to giving over Torah!  Eldad and Meided must be silenced because there is no way their prophecy could be true.

The Maharal In Gevuros Hashem writes that the Torah's explanation for Moshe's name, "ki min ha'mayin mishi'sihu," is not just a reference to the isolated event of his being drawn from the water by Pharoah's daughter.  Water represents chomer, unformed matter.  Water has no shape of its own; it will take on the shape of whatever container you put it in.  The opposite is pure tzurah, something that transcends the chaos of physical matter.  Moshe's name reflects the essence of who he is -- "min ha'mayin mishi'sihu," completely removed from chomer.  Moshe is pure tzurah, pure spiritual essence.  

Rav Hoberman uses this approach to defend the Shach (Y.D. 242), who paskens that one is not allowed to call one's rebbe by name in their presence even if preceded by an honorific, e.g. Rabbi Ploni.  How then could Yehoshua uses Moshe Rabeinu's name?  When Yehoshua used Moshe's name he was not using it as an appellation for Moshe the person, like Joe or Bob or Ploni, but rather he was using it as a description of who Moshe was, someone completely divorced from chomer, like the Maharal explains.  Death is something that can effect only chomer, the physical world.  But Adoni **Moshe** -- ki min ha'mayin mishi'sihu -- pure tzurah, is surely immune to such a fate.
 
 

Proper pronunciation

There is a din of "amor lahem" in birchas kohanim that requires the kohen to articulate the bracha. The Beis haLevi writes that there is no din of shomea k'oneh by birchas kohanim-- it must be spoken and heard (Chazon Ish disagrees.)

In Rav Shteinman's sefer Ayeles haShachar on the parsha 6:23 he quotes a first hand account from someone who learned by the Chofetz Chaim when the yeshiva in Radin was first started.  The CC had to travel to Warsaw after Pesach to take care of the publication of the Mishna Berura and en route, he remarked to this individual that he was worried about being stuck over Shavuos because he was mesupak how to recite birchas kohanim in Poland: must he pronounce the words in Polish accented Hebrew, the way everyone else in Warsaw speaks, or can he pronounce the words in his Litvishe accented Hebrew?  Apparently the CC assumed that the bracha being spoken means pronouncing the words the way everyone else does.

The individual relating the story added that he quoted to the CC from some unnamed sefer that claimed that the Polish pronunciation was erroneous and should be disregard, but the CC paid this no heed.  Later, he learned that the author of the unnamed sefer (any guesses?) was a maskil and that's why the CC, he assumes, ignored it.  Rav Shteinman then adds icing on the cake and claims that he heard from R Zak's, the CC's grandson, that the CC would often deliberately mispronounce the word "atah" as mil'eil instead of milra "l'hotzi mi'lev hamaskilim."

So let me get this straight: the CC deliberately introduced errors into the way he pronounced words in davening just because the maskilim were the one's doing the right thing?  Since when do we deliberately do something wrong "l'hotzi mi'lev...?"

End of the story: the CC duchened using the Litvishe pronunciation.  Adds R Shteinman, it is well known that the Litvishe pronunciation is close to the Teimani pronunciation.

Not sure what he means by that final comment.  Does R Shteinman think the Yemenite pronunciation is most exact and therefore whatever is closest to Yemenite is more correct?  So why not simply duchen using the Yemenite havara?  Or does he mean that since the Litvishe and Yeminite pronunciations are close (are they really?), it is like having 2 eidim that they are the correct havara?  Should we all make sure to read krias shema in a Teimani or Litvishe accent to make sure we are pronouncing the words lichatchila correctly?

Obligation of blind person in mitzvos

R Yehudah holds that a blind person is patur from mitzvos; however, R Akiva Eiger (shu"t 169) qualifies this view and says that even R Yehudah agrees that a blind person is obligated to keep lavim.  His proof: Tos (R"H 33) writes that a blind person can recite a bracha on mitzvos because even though according to R Yehudah a blind person is exempt mdoraysa from mitzvos, he still has a chiyuv mederraban to do them.  The source for the obligation to keep dinim derabbanan (and the source for reciting brachos) is the lav of lo tasur, the lav of not disobeying beis din.  If a blind person is exempt even from lavim, what would obligated him to keep a derabbanan?  How can he recite vi'tzivanu on them?  QED there is a chiyuv in lavim.

There seems to be a Yerushalmi against this view.  The Yerushalmi (13a in vilna pages, end of second perek in sota) darshens from "vne'elan mei'euney isha" that the wife of a blind person does not drink sota water.  The gemara then writes that this follows R Yehudah's view that a blind person is exempt from mitzvos.  

What the Yerushalmi seems to be saying is that since the blind person is exempt from mitzvos, even issurim, there is no problem with him living with his potential sota wife (see Korban Ha'eidah.  The Ohr Sameiach does not understand the Yerushalmi this way, but I don't understand what he is saying.)

So it could be that R Akiva Eiger's chidush is a machlokes Bavli and Yerushalmi.  (Other Achronim take issue with the proof itself.  As we've discussed before, there are reasons other thsn lo tasur that might obligate a person to keep dinim derabbanan.)

Torah as a mitaheir

Imagine you are going out to a great steak restaurant.  You are looking forward to that delicious steak, but decide to start with an appetizer to whet your appetite.  You ask the waiter to recommend something, and he suggests... a steak.  You want a first course before the main dish?  The waiter recommends more steak.  By the time you get to the main dish, you don't even want to see a steak!

We want to appreciate kabbalas haTorah that takes place Shavuos morning, so what do we do?  We stay up all night learning.  Steak before the steak!  By the time the baal koreh gets to aseres hasibros half the shul is asleep, not sitting in excitement and anticipation.

The Zohar writes that on the night of Shavuos the goal is l'natra dachya ila'ah -- one can have great taharah on this night (see post from 2013).  How does one achieve tahara?  Sefas Emes answers: through torah. There is limud hatorah that is done for the sake of knowledge, and there is limud hatorah which purifies and elevates the person.  

Our first course is limud hatorah which is a mitaheir.  That meal, that experience, is completely different than the limud hatorah of the rest of the year.  It transforms a person and makes the rest of learning possible.

Make it a habit

I am not such a big fan of Shavuos all nighters. Rambam writes in Peirush Hamishnayos that it's better to give $1 to tzedaka 100 times than to write one check for $100 because the former inculcates giving as a habit while the lattter does not.  If Shavuos is one and done, then its value (there certainly is some value to spending hours learning even once) is minimized.  If it is something done to be mechazek a regular learning routine, then it makes more sense.

Let's be real: how many shuls have a vasikin minyan on day one of Yom tov, but on the second day davening is scheduled for 9:00, too late to even make zman krias shema?  And how many people show up at 9:15 or 9:30 or later for that minyan?  

And how many shuls get a crowd to sit and listen to lectures for a few hours Shavuos night, but next day and next Shabbos afternoon etc there is not even a minyan (and maybe not even a zimun) of people who have a seder in beis medrash on these long shabbos afternoons?

The spiritual energy of Yom Tov is something that has to be incorporated into everyday life, part of a consistent  routine, not be an oasis in a desert.  

"Yom chasunaso -- zu mattan Torah," the mishna in Taanis tells us.  Imagine a chassan and kallah who have a great wedding, are so happy for a few hours, but then don't talk to each other for weeks afterwards except for maybe a few sentences.  Shavuos is the chassunah and Torah is the kallah.  You can have a great wedding party Shavuos night, but if you then ignore your kallah, if you don't connect with Torah but instead go back to your pre-chasunah routines, what kind of marriage is it?

Toldos Aharon u'Moshe

Rashi (3:1) writes that Aharon's children count as "toldos Aharon **u'Moshe**" because since Moshe taught them Torah it is as if he was their father.

The meforshei Rashi all ask: Moshe taught Torah to all of Klal Yisrael.  What was special about his teaching Torah to Aharon's children that created a father-son relationship?

Maharal in Gur Aryeh answers that without Klal Yisrael to teach to, Torah would never have been given to Moshe.  Moshe was obligated to teach them.  However, what Moshe taught to bnei Aharon was above and beyond what was demanded of him.

What does Maharal mean?  There is no shiur to the mitzvah of talmud torah saying you have to teach others up to point X and no more. There is no point which is above and beyond one's obligation.  So how could what Moshe taught bnei Aharon be above and beyond what was required?

See R Gifter's answer in his Pirkei Torah. 

I would suggest as follows: last night I posted R Wahrman's chidush that for something to be defined as part of the cheftza shel torah it is not enough for Moshe to have received it from Hashem -- it also has to be passed on to others.  A kabbalas hatorah without mesorah of Torah is by definition incomplete.

The chovas hagavra of what one is obligated to teach others has no bounds.  However, perhaps not every detail need be taught before one can say a halacha is part of the cheftza shel torah. As an analogy, it's fair that say someone who knows shulchan aruch with Shach and Taz etc knows basar bchalav, but that doesn't mean they are exempt from continuing to learn those sugyos, as Torah is endless.  What Maharal may mean is that Moshe had to transmit some basic level of Torah to all of Klal Yisrael for there to be a cheftza shel Torah.  However, when it came to the chovas hagavra of limud Torah, the endless depths of learning, he devoted his energies in particular to teaching Aharon's children.

More on shemiras hamikdash

V'atah hafkeid es halevi'im... v'saviv lamishkan yachanu (1:50)

V'halevi'im yachanu saviv lamishkan... (1:53)

Why the repitition?

Earlier in the week I pointed out that the inclusion of the din of shmiras hamikdash in Mes Midos shows that it is a din in the tzuras habayis, not a chiyuv avodah incumbent upon the levi'im.

The Brisker Rav says it's both, and that's why we have 2 pesukim.  

In the first pasuk the din of camping around the mishkan appears in the context of "heim yis'u es hamishkan v'heim yisharsuhu" -- the avodah of leviim.

In the second pasuk it appears In the context of "v'chanu Bnei Yisrael..." -- the tzurah of the encampment.

Similarly, there are two different halachos in the Rambam.  In Beis haBechira 7:11 the Rambam describes the 3 machanos in the midbar and he quotes the pasuk of "saviv la'mishkan yachanu" as the source for establishing a machaneh levi'ah.  This is a din in the tzurah if the encampment. 

In Klei haMikdash 3:2 the Rambam writes "avodah she'lahen hi she'yi'hiyu shomrim es hamikdash" -- shemira is an avodah job assigned to the levi'im.

kabbalas haTorah and mesorah

The Pnei Yehoshua points out a seeming contradiction between the following two gemaras:

1) The gemara (Megillah 2) writes that nevi'im instituted using final letters mem-nun-tzadi-pey-kaf that are different than the regular letters.  Asks the gemara: we have a principle that a navi is not allowed to create a new law; how could they invent this new din?  Answers the gemara: the concept of final letters existed in the past but was forgotten.  The nevi'im were not instituting a new law, they were just re-establishing past practice.  (See Sukkah 46 for a similar idea.)

2) The gemara (Temurah 16) writes that 3000 halachos were forgotten in the days of mourning following Moshe's death.  Asks the gemara: why didn't Yehoshua or Shmuel use nevuah to rediscover those lost laws?  Answers the gemara: a navi has no right to be mechadesh new halachos.  The laws were only restored through the brilliant pilpul of Osniel ben Knaz.

The sugya in Megillah allows for a navi to use the power of prophecy to re-establish laws that were previously known and forgotten, yet the sugya in Temurah tells us that nevuah could not be use to rediscover the halachos forgotten upon the death of Moshe.  How do you resolve the contradiction?

Rav Wahrman in his She'eiris Yosef vol 4 suggests that the two sugyos are addressing two different problems, as the principle of ain navi rashay l'chadesh davar is two dinim in one: 1) the navi cannot use prophecy to rule on halacha; 2) prophecy is not a cheftza shel Torah, but is in a category of knowledge all its own. The gemara in Megillah is addressing the second problem only.  Since final letters existed in the past as a cheftza shel Torah, the navi is not creating new law.  The gemara in Temurah is addressing the former issue, and dealing with the right of the navi as a gavra to pasken using nevuah.  Whether or not these halachos existed in the past is irrelevant to this question, as it is an issue of process, not outcome.

Rav Wahrman (link) in a few parenthetical lines snuck into the middle of the piece offers a possible second answer, which is the one I want to focus on.  He writes  that in order for something to be a cheftza shel Torah it is not enough for it to have simply been received by Moshe Rabeinu.  Torah = mesorah.  For something to become a cheftza shel Torah it has to be passed on to future generations.  The nevi'im who lived generations after kabbalas haTorah were restoring a tradition that had existed once upon a time, but been lost over the years.  However, the halachos that were forgotten immediately upon the death of Moshe were too new, too fresh, to have yet been incorporated into the mesorah.  They were lost right out of the starting gate, at generation 1 after kabbalas haTorah.  When there is no mesorah to start with, a navi has to right to create a new one.

In light of this chiddush I would suggest that the Mishna in Avos that tells us "Moshe kibeil Torah m'Sinau u'mesarah l'Yehoshua" is not telling us about two events, namely 1) kabbalas haTorah and 2) its transmission to Yehoshua, but rather is telling us about one event only: kabbalas haTorah.  What the Mishna is telling us is that a kabbalas haTorah is a true kabbalah only when there is a "mesarah..." that follows -- when the kabbalah impacts and effects the future.

Rashi in Pesachim (68) writes that the chiyuv simcha of Shavuos is  "...l'har'os she'noach u'mekubal yom zeh l'Yisrael she'nitna Torah bo."  R' Shlomo Zalman Auerbach (posted here) was medayek from Rashi that the simcha of Torah that we celebrate on Shavuos is something that we have to show to others, to demonstrate.  Perhaps if kabbalas haTorah is complete only if Torah is given over to others, the simcha of kabbalas haTorah is complete only if we give it over to others as well.

More on aliya laregel

Just to clarify a bit as a follow-up on yesterday's post:

The problem with learning that the Rambam understood that the mitzvah d'oraysa of "yeira'eh kol zechurcha" includes bringing one's children to the Mikdash is that the Rambam himself writes in Hil Chagiga 2:3 that bringing children is "kdei lchancho b'mitzvos" -- a din in chinuch.

You could say the Rambam in Mishne Torah recanted on his position in Sefer Hamitzvos if you like, but that is a bit of a dochak.

To be fair, the Rambam in Mishne Torah continues and adds after "kdei lchancho... she'ne'emar yeira'eh kol zechurcha." So we have to fudge something here-- either the "kdei lchancho" is lav davka or the pasuk is lav davka.

The tzad to say the quote of the pasuk is a lav davka is the fact that the gemara 4a quotes a braysa that uses the same pasuk to explain why a katan is chayav but then reinterprets the braysa to be an asmachta.  The Rambam is simply echoing the braysa's language with the gemara's interpretation (Lechem Mishne).

My son pointed out a piece from R Dovid Soloveitchik in which he argues that this cannot be a regular din of chinuch because the katan does only half the mitzvah -- he comes to the Mikdash, but does not have to offer korbanos (see the meforshei haRambam who point out that this is a machlokes Rashi and Tos).  How can you have chinuch to do half a mitzvah?  He therefore concludes that the words "kdei lchancho" cannot be taken at face value and ketanim come so that their father fulfills the d'oraysa din of "yeira'eh kol zechurcha." Note to that the Rambam does not just say "chayav l'ha'aloso" but adds "l'haros bo," implying a chiyuv on the father to appear with his children.

Sof kol sof: no simple conclusion here.

Shemiras hamikdash

The first mishna in Midos tells us that kohanim stood guard in three places in the Mikdash (leviim stood guard in another 21 locations).  This din is derived from our parsha where Aharon and his sons are told to be "shomrim mishmeres hamikdash" (3:38).  Torah Temimah explains that some varient of the word "shemira" occurs 3x in the pasuk (shomrim, mishmeres, l'mishmeres) and hence we learn that a kohen guard is needed in three locations.

From the placement in our parsha in the context of the discussion of who camps where and the placement of this din in Midos, it seems that this din is not a chovas hagavra obligation on the kohanim, but rather is part and parcel of how the camp should be arranged and how the Mikdash should be setup and built (see Tiferes Yisrael).

According to most Rishonim the chiyuv of shemira is only at night.  Even though the purpose of shemira is to honor the Mikdash -- this is an honor guard, not  a guard to catch thieves -- and therefore there should be no difference between day or night, nonetheless, the tzurah of the mitzvah of shemira matches what would be done if the guards were there for protection.  A shomer by day when not needed does not have a shem shomer.

The anonymous mifareish on MesTamid is the lone view that holds shemira must be done by day as well, and Achronim have such difficulty with this opinion that some claim it is not really what anyone holds.

I prefer conceptual questions to practical ones, but here is what Rashash on the mishnayos in Midos asks: when Moshe gave this mitzvah, there were only three kohanim in the world -- Aharon and his two sons.  If three kohanim were required to do shemira during the day, then who was left to do the avodah?

Aliya la'regel

The Rambam in Sefer Hamitzvos aseh # 53 writes that the mitzvah of aliya la'regel includes bringing along one's sons who can walk. 

This seems to be a strange formulation, as bringing one's sons along is not part of this mitzvah d'oraysa but rather is simply a kiyum of the mitzvah of chinuch.  The Rambam doesn't include the side kiyum of chinuch when he speaks about other mitzvos, so why mention it here?

See Ner Mitzvah in Chemdas Yisrael  (R Meir Dan Plotzki) who leaves this b'tzarich iyun.