Getting back to the Rashi discussion in this post from Friday, I had lined up five questions on Rashi but did not offer any answers (please read that post first or this will make no sense).
The gemara suggested that there cannot possibly be a problem of bal tosif with performing a mitzvah outside its allotted time as long as one has no kavanah, otherwise someone who sleeps in sukkah on the eighth day of sukkos should get malkos. Rashi commented - “d’mosif shmini al shevi’i, v’anan meisav yasvinan b’shmini b’safeik shevi’i l’chatchila – elah, she’lo b’zmano b’lo kavanah lav tosefes hu ul’hachi sharinan, d’i shmini hu lo mechavein l’miztvas sukkah”.
Returning to the questions raised on Friday:
1) What’s bothering Rashi? The gemara’s arguments is in the form of a reduction ad absurdum - you can’t say bal tosif on a mitzvah she’lo b’zmano without kavanah because you would therefore also be forced to say someone who sleeps in sukkah on the eighth day gets malkos. But how do we know that there is no malkos in that case?! Rashi fills in the knowledge gap by reminding us that common practice is to sit in sukkah on Shmini Atzeret because of sfeika d’yoma.
2) The gemara’s language refers to “hayashein”, one who sleeps in the sukkah, but Rashi refers to “meisav” sitting. I think perhaps Rashi is alluding to the fact that our common practice is to eat, but not sleep in the sukkah on Shmini Atzeret, though one could argue that the term “meisav” is a generic term for the mitzvah of yeshivas sukkah in all its forms – eating, sitting, sleeping. I’m just raising the thought.
3) I am a bit perplexed by Rashi’s stress on “l’chatchila”. Perhaps Rashi wanted to avoid the though that there is a potential of bal tosif, but in deference to sfeika d’yoma we sit in sukkah anyway, but this is only a b’dieved concession.
4 a-b) The simple reading of the gemara’s would suggest a scenario of someone in Eretz Yisrael who decided to sit in sukkah for an extra day violating bal tosif. In fact, some Rishonim do present this as the scenario. Going back to question #1, I think Rashi would have wondered why it was so clear that such a person does not get malkos. On the other hand, Rashi raises a different question – if Chazal decreed that there is a Rabbinic obligation to sit in sukkah, that decree may preclude bal tosif (see this post), but who says it would not apply in other cases?
5) The Aruch laNer sees the Rashi in R”H which omits the elaborate scenario as a retraction of sorts – Rashi felt that once the Rabbinic obligation of sitting in sukkah because of sfeika d’yoma is invoked the discussion of bal tosif is moot. However, I would just note that the topic of the two sugyos is different. The focus in R”H is on kavanah, not the issue of zman. Would Rashi perhaps simply feel less pressed to explain why someone is sitting in sukkah during that extra day if the timing is not an issue?