Pesachim 31B

אלא הכא במאי עסקינן ⁠— כגון שהרהינו אצלו, וקמיפלגי בדרבי יצחק. דאמר רבי יצחק: מנין לבעל חוב שקונה משכון? שנאמר: ״ולך תהיה צדקה״. אם אינו קונה משכון ⁠— צדקה מנין? מכאן לבעל חוב שקונה משכון.

Rather, with what are we dealing here? With a situation where he, the non-Jew debtor, deposited the leavened bread that was serving as collateral with him, the Jewish creditor, and they disagree with regard to the statement of R' Yitzḥak. As R' Yitzḥak said: From where is it derived that a creditor acquires collateral given to him, and is considered its owner so long as the item is in his possession? As it is stated: “You should surely return the pledge to him when the sun goes down, that he may sleep in his garment, and bless you; and it should be a righteousness for you before YHWH your God” (Deuteronomy 24:13). R' Yitzḥak infers: If the creditor does not acquire the collateral, then from where is the righteousness involved in returning it? In this case, the creditor would not be giving up anything of his own. From here it is learned that a creditor acquires the collateral.

תנא קמא סבר: הני מילי ישראל מישראל הוא, דקרינא ביה ״ולך תהיה צדקה״, אבל ישראל מגוי ⁠— לא קני.

The Talmud applies this principle to the explanation of the baraita: The first tanna holds that this applies only when a Jew takes collateral from a fellow Jew, such that I would read and apply the verse “It should be righteousness for you” and establish that the collateral becomes the property of the lender. However, the verse does not speak about the case where a Jew takes collateral from a non-Jew, and therefore he does not acquire the collateral; it still belongs to the non-Jew. Therefore, when a Jew has leavened bread as collateral from a non-Jew to whom he lent money on Passover, he does not violate any prohibition, as the collateral still belongs to the non-Jew.