(Mishnah): It is permitted to derive benefit from Chametz that was owned by a gentile over Pesach, but not if it was owned by a Jew, as the verse states (Shemos 13,7), "it may not be seen in your possession''.

If a gentile loaned money to a Jew and took Chametz as his collateral, it is permitted to derive benefit from it after Pesach. But if a Jew loaned money to a gentile and took Chametz as his collateral, it is prohibited to derive benefit.

If a building fell onto Chametz, it is considered destroyed. R''SBG requires that a dog be unable to retrieve it.

(Gemara) Inference: (The Mishnah states that one may derive benefit from Chametz owned by a gentile.) This implies that it would be prohibited to eat it.

The Mishnah is discussing a place where it is the custom not to eat bread baked by a gentile. However, in a place where it is the custom to eat such bread, it is also permitted to eat the Chametz.

Query: Is it permitted (to benefit from the Chametz of a gentile) during Pesach?

Answer: R' Yirmiyah said it is permitted and R' Yosa said it is prohibited.

Question (R' Yosa-Beraisa): A Jew may not rent his animal to a gentile to bring on it Chametz?

Answer: It is prohibited since the Jew will be accompanying him.

Question (Beraisa): A Jew may not rent his boat to a gentile to bring on it Chametz?

Answer: It is prohibited since the Jew will be accompanying him.

Question (Beraisa): A Jew may not rent his house to a gentile in order to put inside it Chametz. Could one answer here that the Jew is living there with him? (Even if the Jew lives there, does it look like the Chametz belongs to him? Furthermore, the phrase 'rent' implies that the Jew has no part of it!)

If the roof of a gentile was next to the roof of a Jew and Chametz of the gentile rolled onto the Jew's roof (during Chol HaMoed), the Jew must push it away with a stick (but not with his hands - lest he eat it). If it happened on Shabbos or Yom Tov, Rav said that one should overturn a vessel onto it.

(Rav): One must declare, "Any Chametz that I have in my house that I am unaware of should be annulled''.

(Rav): One must bless (before checking for Chametz), "...who sanctified us through his mitzvos and commanded us in the mitzvah of destroying Chametz''.

(Rav): One who plastered his house with Chametz must destroy it (by scraping the Chametz from the walls).

Question (Beraisa): R' Shimon ben Elazar taught that a dough that was made into a seat is considered nullified?

Answer #1: Rav disagrees with R' Shimon ben Elazar

Answer #2: The seat is different as it has become repulsive.

(Tosefta): If a Jew and a gentile are travelling in a boat and the Jew possesses Chametz, he should sell it to the gentile or give it to him as a gift and then reacquire it from the gentile after Pesach, as long as he gives it to him as an absolute gift.

Explanation: The Jew should say to the gentile, "Instead of buying (a small quantity) for 100, buy (a large quantity) for 200. Instead of buying it from a gentile, buy it from a Jew; perhaps I will need to buy it back from you after Pesach (and you will make a profit on it)''. (Note: The parenthetical additions follow the explanation of Rav Chaim Kanievski).