We don't say a Gezairah Shavah but only half of it a A "Gezairah Shavah Lachatzoin". So we should say by Sukka and Matzah we learn a Gezairah Shavah because it says Chamishoh Osor (15) by Sukka and Chamishoh Ossor (15) by Matza. So we learn out that you have to have a Kezayis (olive size) of Challah in the Sukka because of the Gezairah Shavah. My question is, why don't we learn out that you have to eat in the Sukka on Pesach and eat Matza on Sukkos so you are not learning half a Gezairah Shavah? Then it wouldn't be a Gezairah Shava Lachatzoin. We should also learn out that since women have to eat a Kezais of Matza on the 1st night of Pesach they have to eat a Kezayis of Challa in the Sukka on the 1st night of Sukkos?
A similar question was asked previously on our forum. Below we have inserted that question and its answer.
Kollel Iyun Hadaf
Shabbos 131b: Kal va'Chomer to eat Matzah on Sukos
Why don;t we make a kal vechomer that surely pesach where you have to eat matzah and u don't sit in a sukkah, yet you have to eat matzah...surely sukkos where u have to sit in a sukkah u should have to eat matzah!?!?!
levi, brooklyn ny
The Kollel replies:
There are many possible Pirchos to your Kal vaChomer, which show that Pesach is more Chamur than Sukos. For example, Chametz is Asur on Pesach but not on Sukos, so, too, we are required to eat Matzah only on Pesach (and we cannot learn an Onesh for eating Chametz on Sukos from the same Kal va'Chomer, since Ein Onshin Min ha'Din).
Actually, the Gemara links Sukos to Pesach with a Gezeirah Shavah (Shabbos 131b). If so, even a Pircha should not stop us from applying the laws of Pesach to Sukos. Why then is there no Mitzvah of Matzah on Sukos (or sitting in a Sukah on Pesach)?
The Toras Kohanim (Emor, Perek 11:2) indeed learns from the word "ha'Zeh" that we do not eat Matzah on Sukos, and (in Parshah 12:2) that we do not sit in a Sukah on Pesach.