On this daf, we find some discussion about the korban chagigah.
One man’s mezuzah fell on Shabbos and he had no idea what to do. He knew for sure that he couldn’t put it back up until after Shabbos, since that was surely forbidden. He saw that the Pri Megadim writes on the Magein Avrohom in 38:15 about just such a case that one is permitted to live in the house until after Shabbos. Yet, he knew that if one declares a room ownerless, it does not require a mezuzah. Since the Ritva in Eiruvin (71) writes that one may declare something ownerless on Shabbos for the sake of a mitzvah, perhaps that was better.
When this question was presented to Rav Yitzchok Zilberstein, he ruled as follows: “In Pesachim 70, we find that Rav Yehudah Ben Durdai held that one must offer a chagigah even on Erev Pesach that falls out on Shabbos. Since the sages held that this is forbidden, he left Yerushalayim to a distant place so that he would not be obligated to ascend to the Bais Hamikdosh and offer a Korban Pesach but not a chagigah.
“In this situation, he was surely an oneis, since he could not offer the chagigah, so why did he leave Yerushalayim? We see that if one can remove his obligation in a mitzvah, it is preferable to do so than to be an oneis. The same is true in this case, as the Mikdosh Me’at rules, so he should declare the room ownerless on Shabbos” (Chashukei Chemed; Mikdosh Me’at brought in Seichel Tov, p. 59).
