1) SITTING IN A SUKAH IN THE RAIN
QUESTION: The Mishnah states that one is permitted to leave the Sukah when it rains, but only when the rain is enough to spoil the "Mikpeh" (a certain type of thick, cooked dish). The Mishnah implies that one is merely permitted, but not required, to leave the Sukah. This seems to be the ruling of the REMA (OC 639:7) who writes that one who eats in the Sukah in the rain does not receive any reward for his act, and he is called a "Hedyot," a fool. The Rema's words imply that there is no prohibition to stay in the Sukah in the rain. Rather, one merely fulfills no Mitzvah by doing so.
The ONEG YOM TOV (OC 49) asks that the SHULCHAN ARUCH (beginning of OC 638) rules that the wood used to build a Sukah is prohibited mid'Oraisa to be used for any other purpose for the duration of the festival, as the Gemara (9a) says. This prohibition includes both the wood of the walls and that of the Sechach. The Rema there adds that even a verbal stipulation before the festival does not permit the wood in the event that the Sukah collapses.
The Gemara (Rosh Hashanah 28a) teaches that when a person makes an oath not to derive any benefit from a house, he is not permitted to sit in the house. This implies that sitting in a house is considered a form of benefit from the house. Similarly, sitting in a Sukah is considered a form of benefit from the Sukah.
Accordingly, one should be prohibited from sitting in the Sukah when it rains, since he does not fulfill the Mitzvah at that moment and he derives personal benefit from the walls and Sechach which protect him from the rain. Why, then is he permitted to remain in the Sukah when it rains?
The Oneg Yom Tov suggests that perhaps the prohibition to derive personal benefit from the wood and Sechach of a Sukah applies only to forms of usage that conflict with the Mitzvah of Sukah (as TOSFOS implies in Shabbos 22a), such as when one dismantles the Sukah to use its wood.
However, he counters that this suggestion is implausible for a number of reasons. First, the Gemara in Shabbos (22a) says that one may not count money in front of the Chanukah lights because of "Bizuy Mitzvah" (disgrace to the Mitzvah). This implies that even when there is no prohibition against using the Mitzvah object for personal use (because of "Huktzah l'Mitzvaso"), there still should be a prohibition against disgracing the Mitzvah object ("Bizuy") by using it for personal use. Second, the Gemara later in Sukah (37b) says that one may not smell a Hadas branch which has been set aside for the Mitzvah of Arba'as ha'Minim, because it is "Huktzah l'Mitzvaso." Smelling the Hadas does not conflict with the Mitzvah for which the Hadas was designated, and yet the act is still prohibited. Third, the Gemara earlier (9a) compares the Mitzvah of Sukah to the Mitzvah of Korban Chagigah. Just as one is prohibited to derive benefit from a Korban Chagigah in any manner, even if that benefit does not conflict with the Mitzvah, so, too, one should be prohibited to derive any form of benefit from a Sukah.
Why, then, is one not prohibited from sitting in a Sukah when it rains?
(a) The ONEG YOM TOV answers that the Torah's prohibition against using the material of the Sukah for personal benefit does not apply when a Sukah collapses. In such a case, to benefit from the Sukah is prohibited only mid'Rabanan (as the MISHNAH BERURAH (OC 638:5) writes). Similarly, perhaps when one covers the top of the Sukah (and temporarily renders it invalid), he is prohibited only mid'Rabanan from using the Sukah for personal benefit. If the prohibition is only mid'Rabanan, then it is likely that the Rabanan did not prohibit one from deriving personal benefit from the Sukah through as simple an act as sitting in the Sukah when it rains, because such an act is in no way disgraceful to the Sukah.
Why, though, should one be permitted to sit in a Sukah when it rains when the Sukah is not covered?
The Gemara says that "the Torah was not given to angels" (Yoma 69a). For that reason, the Kohanim are permitted to wear the Bigdei Kehunah even after they have completed the Avodah, because it is impossible to remove the clothing at the very moment that they complete the Avodah. For the same reason, one should be permitted to sit in a Sukah after the Mitzvah of Sukah has been completed.
This logic, though, should apply only when one was in the Sukah before it started to rain. In such a case, he may remain in the Sukah even though he no longer fulfills the Mitzvah, because "the Torah was not given to angels." Why, though, may one enter a Sukah when it is already raining? Perhaps the principle that "the Torah was not given to angels" removes the Torah prohibition to enter the Sukah in the rain and makes it prohibited only mid'Rabanan. If the prohibition is mid'Rabanan, then perhaps the Rabanan did not apply the prohibition against benefiting from a Sukah in a situation where one merely wants to sit in the Sukah in the rain, since that act is not disgraceful to the Sukah.
(b) The CHAZON YECHEZKEL (2:5) writes that the reason why one may sit in a Sukah in the rain is the reason that the Oneg Yom Tov initially suggested and then rejected. The prohibition applies only to forms of usage that conflict with the Mitzvah of Sukah. One may not benefit from the Sukah when that form of benefit detracts from its utilization as a Sukah.
In the case of the prohibition against smelling the Hadas, it is clear from the Gemara that the only reason smelling is prohibited is because the Hadas is commonly used for its aroma. When one designates the Hadas for the Mitzvah, he thereby sets it apart from its most common use. This is in contrast to the Esrog, for example, which one is permitted to smell during Sukos because its most common use (the rest of the year) is not its aroma. The prohibition against smelling the object of a Mitzvah applies only to a Hadas, and not to other Mitzvah objects. (The RASHBA adds that if one uses Hadas branches as the walls for his Sukah (because fragrant wood makes good walls), then he is permitted to smell them during Sukos. This is because he uses it only as a piece of wood and not as the object of an actual Mitzvah.)
When the Gemara earlier (9a) compares the Mitzvah of Sukah to the Mitzvah of Korban Chagigah, the Gemara's intention is to teach that just as an object is Kadosh because it is designated to be used for a Korban, so, too, an object (such as a Sukah) can become "set aside (Huktzah) for a Mitzvah" when it is designated for a Mitzvah. The comparison does not teach that one is prohibited to derive any form of personal benefit from a Sukah just as one is prohibited to derive any form of benefit from a Korban Chagigah, even if that benefit does not conflict with the Mitzvah.
(The Chazon Yechezkel does not address the question from the Gemara in Shabbos (22a), which says that one may not count money in front of the Chanukah lights. Perhaps there is an obvious difference between the two cases. There, it is clearly a disgrace to the Mitzvah of the Chanukah lights for one to count money in front of them. In the case of one who sits in a Sukah to protect himself from the rain, he merely sits underneath the object of the Mitzvah, an act which is not disgraceful to the Mitzvah.)
The Chazon Yechezkel cites support for his answer from the Gemara earlier (10b). The Gemara there relates that the servant of Rav Ashi placed a wet cloak on top of the Sukah to dry. Although that act involved benefiting from the Sechach of the Sukah, it was permitted because it did not detract from the use of the Sukah.
(This approach also seems to be the view of TOSFOS in Shabbos 42b, DH v'Ein, and 45a, DH Ela. Tosfos there explains that a flame that was lit for use as a Shabbos light may be moved (according to Rebbi Shimon), because moving it does not detract from the Mitzvah. One is prohibited, however, to use the oil that drips from the lamp, because at the time the flame was lit the removal of the oil would have detracted from the Mitzvah.)