Shalom,
Towards the bottom of daf lamud amud aleph Rava challenges Rav Nachman bar Yitzchak's challenge to R' Yitzchak bar Nachmani and says the Mishnah is discussing the first day of Sukkos. Rava explains that it was unnecessary for the Mishnah to include borrowed because for certain it is not the thief's. But, the Mishnah needed to teach about a stolen lulav because the havaaminah is that with a stolen lulav the owner will have yeush and therefore the thief could be yotzei. The Mishnah teaches that the owner will not necessary have yeush according to Rashi.
Even if the owner had yeush and the thief heard him give up hope how would that help since it would be a mitzvah haba-ah b'aveirah? Does Rava not hold by a mitzvah haba-ah b'aveirah?
Thank you for your help.
Avraham Sacks
Avraham Sacks , Ramat Beit Shemesh
We can give an answer based on an idea of the Tosfos Yom Tov in chapter 3, Mishnah 1 (DH ha'Gazul). He writes that the concept of Mitzvah ha'Ba'ah b'Aveirah is derived from a verse in Yeshayahu 61:8: "I am Hash-m, Who hates a stolen Olah." In contrast, we learn from a verse of the Torah that a stolen Lulav is invalid.
Therefore, Rava said that the Mishnah teaches that the owner does not have Ye'ush, and this means that the Lulav is invalidated by a Torah verse. Rava does indeed hold of the rule that a Mitzvah ha'Ba'ah b'Aveirah is disqualified, but he wants to show that the stolen Lulav is disqualified by a Torah verse, which is even more basic than a verse in Navi.
Kol Tuv,
Dovid Bloom