shemita, ona'ah. and lag ba'omer

Our parsha opens with the sugya of shemita and yovel, and then proceeds to tell us the halachos of ona'as mamon and ona'as devarim.  The parsha then returns to the sugya of shemita/yovel, and responds to the farmer's worry (25:20-21):

וְכִי תֹאמְרוּ מַה⁠ נֹּאכַל בַּשָּׁנָה הַשְּׁבִיעִת הֵן לֹא נִזְרָע וְלֹא נֶאֱסֹף אֶת⁠ תְּבוּאָתֵנוּ

 וְצִוִּיתִי אֶת⁠ בִּרְכָתִי לָכֶם בַּשָּׁנָה הַשִּׁשִּׁית וְעָשָׂת אֶת⁠ הַתְּבוּאָה לִשְׁלֹשׁ הַשָּׁנִים

Why does the Torah wait until after the parsha of ona'ah to respond to the farmer's concern about going hungry during shemita and yovel?  Shouldn't these pesukim appear earlier?

My wife's grandfather, R' Dov Yehudah Shochet, answers (see my wife's post here)  that the very same worry of  מַה נֹּאכַל that the farmer feels free to openly express (וְכִי תֹאמְרוּ...) during the shemita year also lives in the back of the mind of the person who violates the issurim of ona'ah.  It's the fear of not being able to make a go of it unless you chisel more out of the other guy, or put down the other guy so that you are not left with less.  If you trust that Hashem will always give you your fair share, then overcharging the next guy accomplishes nothing. Therefore, the Torah waits and puts the response of וְצִוִּיתִי אֶת בִּרְכָתִי לָכֶם after the parsha of ona'ah, as the message of bitachon, the message that Hashem will ensure you get what you deserve, undercuts not just the worry of shemita observance, but undercuts the temptation for ona'ah as well.

This same theme is at the root of our celebration of Lag baOmer.  The Yerushalmi (Sheviis 9:1) records that when Rashb"i came out of the cave, he saw a hunter trying to trap birds.  He heard a voice in shamayim declare that the bird should go free, and off flew the bird.  He heard a bas kol declare that a bird should be caught, and so it was:

רִבִּי שִׁמְעוֹן בֶּן יוֹחַי עֲבַד טְמִיר בִּמְעַרְתָּא תְּלַת עָשָׂר שְׁנִין בִּמְעָרַת חָרוּבִין. (דתרומה)  עַד שֶׁהֶעֱלָה גוּפוֹ חֲלוּדָה לְסוֹף תְּלַת עָשָׂר שְׁנִין. אֲמַר לֵינָה נְפַק חָמִי מַה קָלָא עָֽלְמָא נְפַק וְיָתִיב לֵיהּ עַל פּוּמָא דִמְעַרְתָּא חָמָא חַד צַייָד צְייַד צִיפּוֹרִין פְּרַס מְצוּדָתֵיהּ שְׁמַע בְּרַת קָלָא אָֽמְרָה דִימִוס וְאִישְׁתֵּיזְבַת. אֲמַר צִיפּוֹר מִבַּלְעֲדֵי שְׁמַיָּא לָא יִבְדָּא. וְכָל־שֶׁכֵּן בַּר נַשָּׁא

Rashb"i concluded that if the fate of birds is determined by hasgacha pratis, kal v'chomer the fate of man.  

It's not our own efforts and actions that determine our success or failure.  Working an extra day, an extra year more than everyone else, charging more than everyone else, will get you nowhere.

Chasam Sofer in his derashos cites a Midrash that says that the matzah from Egypt lasted until 15 Iyar, and then Bn"Y went three days with nothing. They complained (Shmos 16:3):

וַיֹּאמְרוּ אֲלֵהֶם בְּנֵי יִשְׂרָאֵל מִי יִתֵּן מוּתֵנוּ בְיַד ה׳ בְּאֶרֶץ מִצְרַיִם בְּשִׁבְתֵּנוּ עַל סִיר הַבָּשָׂר בְּאׇכְלֵנוּ לֶחֶם לָשֹׂבַע כִּי הוֹצֵאתֶם אֹתָנוּ אֶל הַמִּדְבָּר הַזֶּה לְהָמִית אֶת כׇּל הַקָּהָל הַזֶּה בָּרָעָב

This is the desert version of the farmer's complaint of מַה נֹּאכַל בַּשָּׁנָה הַשְּׁבִיעִת.  On 18 Iyar = Lag Ba'Omer Hashem responded by giving the people mon.  In other words, on 18 Iyar Hashem fulfilled וְצִוִּיתִי אֶת בִּרְכָתִי לָכֶם -- sans hishtadlus, sans any effort, food literally fell from the sky.  

Rashb"i, the baal hilula,opined (Brachos 35b)

 ר"ש בן יוחי אומר אפשר אדם חורש בשעת חרישה וזורע בשעת זריעה וקוצר בשעת קצירה ודש בשעת דישה וזורה בשעת הרוח תורה מה תהא עליה אלא בזמן שישראל עושין רצונו של מקום מלאכתן נעשית ע"י אחרים שנא' ועמדו זרים ורעו צאנכם וגו'

What the famer lived for one year, what we live one day out of seven, Rashbi lived year round (perhaps this is why the Zohar refers to tzadikin as "shabbos.")

Coming back to the opening of our parsha:

 דַּבֵּר אֶל בְּנֵי יִשְׂרָאֵל וְאָמַרְתָּ אֲלֵהֶם כִּי תָבֹאוּ אֶל הָאָרֶץ **אֲשֶׁר אֲנִי נֹתֵן לָכֶם** וְשָׁבְתָה הָאָרֶץ שַׁבָּת לַה׳.

Do we need a reminder that Eretz Yisrael was promised to us by Hashem -- הָאָרֶץ אֲשֶׁר אֲנִי נֹתֵן לָכֶם -- a fact we know from many earlier places in the Torah?  (See Oznayim laTorah)?  

In light of the above, perhaps we can say that these pesukim perhaps set the stage for us for the rest of the parsha.  It's the recognition that Hashem is in chage that makes the observance of shemita, yovel, avoiding ona'ah, all possible.  If you think you are the baal ha'bayis, that your actions alone that determine success or failure, then you are walking into the parsha with the wrong attitude from the get-go.