Siman 666

Even if he finished his meal on the morning of the seventh day, and in the Land of Israel where he does not need to sit in it on Shemini Atzeret—nevertheless, he should not dismantle his sukkah entirely, for he must sit in it all day until nightfall. And perhaps a meal will happen to come his way, and he will need to eat in the sukkah. However, the vessels that are needed for the house—he brings them down from the sukkah from the time of mincha and onwards. And it appears that this is from mincha ketana, for then it is evident that he acts for the honor of the Yom Tov, and is preparing the house for the honor of the final Yom Tov, and there is no disgrace to the sukkah in this.

And if he does not have a house, and he is forced to sit also on the eighth day in the sukkah in the Land of Israel, it appears like "bal tosif"; for there is no absolute "bal tosif," because we hold that to transgress "bal tosif" when it is not its time—one requires intent for the sake of the mitzvah (end of the third chapter of Rosh Hashanah), but otherwise—he does not transgress "bal tosif." But nevertheless the matter is unseemly, and the sages said (48a) that one must invalidate the sukkah, meaning to diminish the s'chach in a place of four by four. And even though it is also invalidated with three tefachim of airspace—nevertheless there is not such a recognizable sign. And it is a simple matter that if he needs to eat again on the seventh day—that he must eat in the sukkah. And know that the concern to avoid "bal tosif" is only on the eighth day, and in the diaspora on the ninth day, because they are adjacent to the days of Sukkot. But one who wants to eat after the festival in the sukkah—does not need anything, for then it does not appear like "bal tosif." And he does not need to diminish it, nor to spoil it, and he sits and eats.

And this is all in the Land of Israel. But in the Diaspora – one does not need to do anything on the seventh day, for one must sit in it on Shemini Atzeret. And on the eighth day, what shall he do? When he has finished eating – he brings down his vessels from the afternoon and onwards to his house, for the sake of the honor of the final Yom Tov. And even though he exerts himself from the first day for the second – nevertheless, it is impossible in any other way, for at night it is impossible to bring them down. And also there is no exertion in this, for he does not set them up properly in the house until the night, and merely bringing them down is of no concern to us.

And what should one do in the Diaspora when he does not have a house, and is forced to eat in the sukkah even on the ninth day, so that he does not appear as one who adds? And to diminish it is impossible, for on a Yom Tov it is forbidden to diminish. The sages said (ibid.) that he should do thus for a distinction: that if it is a small sukkah in which it is forbidden to place the lamp on other days, as I wrote in siman 639 – he should place the lamp in it. And if it is large, in which it is permitted to place the lamp – he brings into it pots and bowls and the like, which are forbidden to be brought into the sukkah, as is explained there, in order to make it known that he is disqualifying it and that its mitzvah has already concluded. And then it does not appear as "bal tosif."

And know that the Rosh, of blessed memory, at the end of Sukkah, inferred from the commentary of Rashi there, that even in the diaspora one must make some distinction on the seventh day in the sukkah, to indicate that what one will eat there on the eighth day—it shall not be as "bal tosif." And he rejected this, see there. And also, in truth, there is no such absolute proof from Rashi, see there. However, it appears to me that the essence of this matter depends on the manner of our sitting on Shemini Atzeret, and it will be explained in siman 668. (The Rosh seized upon what Rashi wrote on 48a in the entry beginning "Ha lan"—for the people of Babylonia one lights the candle, that it refers to the seventh day. And it is possible to say that it refers to the eighth day, and see Bach and Korban Netanel there.)