Let a little water be brought; wash your feet and lean under the tree. (Breishis 18/4)
Zera Shimshon asks a few questions concerning the way Avraham dealt with his guests. Firstly, how could it be that Avraham, who was the epitome of chessed and hospitality, left his guests leaning under a tree outside, and didn’t give them a nice comfortable seat in his tent?
Secondly, Rashi explains that he told them to wash their feet so that there will be no trace of Avodah Zarah. Why after they washed their feet didn't he invite them into his house?
Thirdly, it is written in the Medrash (Medrash Rabah Parshas Noso 14/2), "Whatever Avrohom did for the travelers (angels) Hashem compensated his children, not only once but three times; when they were in the Desert, when they entered Eretz Yisroel, and in the future. Avrohom said to the malachim"...and recline under the tree. Hashem compensated Avrohom's children (Bnei Yisroel) in the Desert, like it says, "that I commanded Bnei Yisroel to dwell in booths (sukkos) when I brought them out of the land of Mitzrayim". From where do we learn that we were compensated in Eretz Yisroel? (It is written) in succos you should dwell seven days". From where do we learn that they will be compensated in the future? It is written"... which shall serve as a booth (succo) for shade from the heat by day and as a shelter for protection against drenching rain."
In other words, Avraham was rewarded for the way he attended the melachim in that his descendants dwelled in succos in the desert, were commanded to sit in succos when they entered Eretz Yisroel and will once again be protected by succos in the days of Mashiach.
Zera Shimshon asks, that Hashem rewards people when they do something extraordinary. However, regarding Avraham and the melachim he didn't give them "royal treatment" at all. On the contrary, it seems that he gave them only second class care. Why then should his descendants be rewarded three times for what seems to be Avraham's mediocre dealing with his guests?
Zera Shimshon begins to answer these three question by first explaining the depth of the mitzvah of Sukkah.
Chazal teach us that Hashem gave Bnei Yisroel in the Desert three gifts; Manna in the merit of Moshe, a spring that traveled with them in the merit of Miriam and the Divine Clouds (ananei hakovod) in the merit of Aharon. It is written in Parshas Emor (Vayikra 23/43) that the Yom Tov of Sukkos is "l'maan yaidu dorosaichem key b'sukkos hoshavti ess Bnei Yisroel"- in order that your future generations will realize that I placed Bnei Yisroel in sukkos.... Zera Shimshon asks why did Hashem designate a Yom Tov to remember the Ananei hakovod, but Hashem didn't give a Yom Tov to remember the spring or the manna. They were also great miracles and very beneficial for Bnei Yisroel?
Zera Shimshon answers this question in light of the Medrash (Pesikata d'Rav Cahana 29) that the reason the Yom Tov of Succos immediately follows Yom Kippur is that if a person didn't act properly the previous year and Hashem decreed that he be punished by being exiled, the going into the succah, in which we leave our comfortable houses, should be in place of actual exile. In other words, living in succah is a "mini-exile" that can exempt a person from an authentic exile.
At the Bris Bain Habessarim Hashem decreed that Avraham's descendants would have to suffer four exiles to purify and perfect them. The first one was in Mitzrayim and when Bnei Yisroel left Mitzrayim they knew that there were three more waiting for them. Chazal also teach us that if Bnei Yisroel would not have served the Golden Calf, the aigel, Bnei Yisroel would have been exempt from exile and servitude to the nations of the world. The question arises however, if that would have been the case what would have happened to the promise of three more exiles? They were part of the covenant between Hashem and Avraham. Hashem therefore right after they left Mitzrayim commanded Bnei Yisroel to dwell in succos so in the case that Bnei Yisroel would pass the test of the Golden Calf, Hashem would count this "mini-exile" as if they went through a full-fledged exile.
This is the reason that there is a Yom Tov to remember the Annanay Hakovod and there are no Yamim Tovim to remember the Manna and the traveling spring. Succos is not only to remember the protection that the Annanay Hakovod provided for Bnei Yisoel, but rather it is to remember the care that Hashem showed us by building Annanay Hakovod around us exempt Bnei Yisroel for future galius.
According to this, Zera Shimshon explains that Avraham Avinu knew that his descendants, Clal Yisroel, will not always conduct themselves properly and he was distressed what will be with them when they will being exiled from the Eretz Yisroel. He therefore, kept his guests in a state of a "mini-galus", outside leaning on a tree, so Hashem will also treat Bnei Yisroel with chessed when they are in galus. True, regarding the travelers it was an incomplete chessed however with regards to his descendants it was a complete chessed. At the time that he attended the guests he prayed that just like he took care of and eased the discomfort of these travelers when they were in transit, so too Hashem should take care of and ease the agony of his descendants when they are in exile.
