Siman 637

One who did not make a sukkah before the festival, whether inadvertently or intentionally, makes his sukkah during the days of the festival, even at the end of the days of the festival. And we do not require a sukkah for all the days of the festival. And that which is written: "The festival of Sukkot you shall make for yourself seven days" – on the contrary, its explanation is that all seven days you are able to make for yourself a sukkah (Gemara 27b). Therefore, a person is permitted to leave his sukkah in the middle of the festival and sit in another, and even in several sukkot (ibid.), for each day is a mitzvah unto itself. Therefore, a minor who became an adult during the days of the festival is obligated in sukkah for the remaining days. And so too, a convert who converted in the middle of the festival is obligated in sukkah for the remaining days (ibid.).

One fulfills the obligation with a borrowed sukkah, and similarly one fulfills the obligation with a sukkah of partnership, but one does not fulfill the obligation with a stolen sukkah. And the reason for the matter: even though it is written "The festival of Sukkot you shall make for yourself," and it should have implied: "for yourself" – and not of partnership, "for yourself" – and not the borrowed, like lulav where it is written "And you shall take for yourselves," and we derive it so; however, since it is written "All the citizens in Israel shall dwell in sukkot," and it is written "basukkot" deficient, which implies that all of Israel shall dwell in one sukkah. And automatically, there would not reach to each one the value of a perutah. And automatically, we hear from this that one fulfills the obligation with that of partnership and with a borrowed one, for perforce it is like a borrowed one. Rather, this "for yourself" – is to exclude the stolen (Gemara ibid.).

The Tur wrote in the name of Rashi (31a) that you do not find a stolen sukkah except when one stole a sukkah made on the deck of a ship or on the top of a wagon. For if one overpowered his fellow and removed him from his sukkah—we hold the principle that land cannot be stolen. And if one stole wood and used it for sechach—he owes him only the value of the wood, even if he did not change them in any way, and he fulfills his obligation with it ex post facto. But the author of the Ittur wrote that if one stole wood and used it for sechach and does not wish to pay their value—it is also considered stolen. Thus far his words. That is to say: the sages enacted for the sake of the "ordinance of the penitent" that if one stole wood and used it for sechach—he does not need to return the wood itself, but rather the value of the wood. Therefore, according to Rashi, even if he did not pay—there remains only a debt upon him, but the wood is his, and there is no theft here. But according to the Ittur, if he did not pay him—the wood returns to the victim, and it turns out that it is a stolen sukkah. However, a sukkah on a ship or on a wagon which is mobile—there was no enactment of the sages regarding this, and according to everyone it is stolen, and he is obligated to return it (and the Magen Avraham decided in accordance with the Ittur).

The same law applies if Reuven built a sukkah on Shimon's land without his knowledge, and Shimon overpowered Reuven and removed him from his sukkah, and stole it and sat in it—he has not fulfilled his obligation, for Reuven possesses only movables, namely the wood, and they are stolen and he must return them, as the enactment for the penitent does not apply here. And it is not similar to one who stole wood and used it for sechach, where he owes only the value because he labored in the placement of the sechach. But here, the thief did not labor in it and did not incur expenses for this, and he is obligated to return the wood itself, and it turns out that he is sitting in a stolen sukkah. However, if Reuven built there with Shimon's knowledge, as he lent him the land for the seven days of the festival, and Shimon overpowered him and removed him, and sat in it—he has fulfilled his obligation, because for all seven days the land is like Reuven's, and that which is attached to the land is like the land and is not stolen, and it is like a borrowed sukkah. And there is one who wishes to say that even without his knowledge this is not included, for land is not stolen (Magen Avraham, subsection 7). But the primary view is like the first opinion (and so wrote the Bach and the Gra"z).

And all this is ex post facto. But initially, a person should not sit in his fellow's sukkah without his knowledge, unless he knows that he is not particular about it. And the default is such, for a person is pleased that a mitzvah be performed with his property (Taz). But if he is particular, or at a time when he himself is there, for presumably he is particular that another not sit there at that time—one should not sit there without his knowledge. And all the more so is it forbidden to initially build a sukkah on his fellow's land without his knowledge. And so too on land that belongs to the public—he should not build a sukkah, for who can give permission? However, in the courtyards of synagogues it is customary to build, for certainly it is pleasing to the public that a Jew fulfill the mitzvah of sukkah. Nevertheless, in the public domain they should not build, and if they built—they have fulfilled the obligation, and they recite the blessing over it. (And the words of the Magen Avraham, subsection 3, are not compelling; see there.) And so too if a man's wife gives permission to another to sit in her husband's sukkah, or to build a sukkah in his courtyard—he may sit and build, for presumably such is also her husband's will. But his son or one of the members of the household—he should not give permission, and his giving of permission is not effective. And it is possible that in a time of pressing need even their giving of permission is effective, for presumably they know that it is pleasing to the owners that another perform a mitzvah in their sukkah, or build a sukkah on their land. And so too, Jews should be careful not to cut the sechach themselves, if there is no permission for everyone to cut sechach for his sukkah. For anything stolen—one does not initially make a sukkah from it. Rather, he should buy it from a non-Jew, for he acquired it through a change, and it came into their hand permissibly.