Generally speaking, the Halacha states that one should leave the Sukkah and go back into the house when it rains. This may not be true, however, on the first night of Sukkos.
Let’s understand why that is exactly. Pesach celebrates the exodus from Egypt and Sukkos celebrates the immediate aftermath. Yet they are connected even more deeply. The Gemorah tells us that many of the halachos that apply to Pesach also apply to Sukkos through the notion a Gzeras Shaveh. A Gzeras Shaveh is likened to a back-end circuit, lehavdil, connecting two words in the Torah to each other. The laws of one section of the Torah thus can be connected and derived from the other section of the Torah. There is such a connection between the words “the fifteenth” stated in Pesach to “the fifteenth” stated on Sukkos.
Just as there is a Mitzvah to eat Matzah on the first night of Pesach – there is also a Mitzvah to eat a K’zayis of bread on the first night of Sukkos. And we must eat it in the Sukkah. It must also be eaten at night.
The question arises as to whether this “back-end circuit” is dealing with a new aspect of the obligation of Sukkos or is it an extension of the Mitzvah of Sukkah that we knew already? According to the Ran – it is a new obligation – and therefore the general laws of Sukkah – don’t apply here. Therefore, even if one is Mitztaer – one is uncomfortable in the Sukkah – one must still eat in the Sukkah. According to the Rambam, it is the same obligation of the general laws of Sukkah that is being discussed. The exemption of rain, according to the Rambam still exists.
The Ramah (Orech Chaim 639:5) rules like the Ran. The Vilna Gaon rules like the Rambam. The Mishna Brurah rules that we must make an effort to wait in order to avoid any doubts.
How long should we wait? Rabbi Abraham Gumbiner, athor of the Mogain Avrohom writes that we should wait until the very last moment – midnight just like on Pesach! The Mishna Brurah, however, rules in accordance with other authorities that the waiting time has not been quantified and it depends upon each and every person.
Therefore on the first night of Sukkos a family should wait approximately one hour to see whether or not the rain will stop. If the rain does not stop, they should go into the Sukkah and recite Kiddush with the Shehecheyanu but without the Laishev BaSukkah. One should wash and say HaMotzi and eat a Kezayis of Challah in the Sukkah. They should then continue the meal in the house. If it stops, one should enter the Sukkah and eat a Kebaitza of Challah in the Sukkah and recite the Laishev BaSukkah. Even if the meal has ended, one should wash again and recite the hamotzi and the Laishev Basukkah. One should do this until Chatzos at night. This year 2012 Chatzos is 12:46 in New York City.
On the second night, one may start the meal in the house immediately – without waiting that hour, although the Mishna Brurah rules that it is also preferable to wait. We say Kiddush with the Shehecheyanu in the house, but have in mind that you may eat a kezayis of Challah in the sukkah at the end of the meal. At the end of the meal before bentching one should still go into the Sukkah and eat a kezayis of Challah, then you can come back and bentch in the house. While in the Sukkah do not recite a Laishev BaSukkah unless it has stopped raining. Once again the timing is until 12:46. If it stops raining before this time, wash and recite the bracha of Laishev in the Sukkah. Why? Because the Kezayis eaten in the rain does not count according to the Rambam, we must try again until 12:46.
Let’s not forget once again that the Sukkah is a manifestation of “HeviAni HaMelech Chadarav – The King has brought me into His inner room (Shir HaShirim 1:4).” After the Yomim Noraim where Klal Yisroel has been elevated and purified, Hashem has given this Mitzvah of Sukkah. The Sukkah’s holiness is a revelation of Hashem’s intense love for His people – a love comparable to the love demonstrated when He was with us in the Bais HaMikdash itself. We should therefore make every effort to fulfill this Mitzvah in all the details explained above.