שולחן ערוך אורח חיים · סימן תמ״א

English

A non-Jew who lent to an Israelite on his Chametz and took it as a pledge in his hand, and said to him: "From now it shall be yours if I do not repay you by a certain time," and the time arrived and he did not repay him, it is permitted even if the time he set did not arrive until after Pesach. Since when the time arrived and he did not repay him, it is acquired by him retroactively, and thus it is considered to be the Chametz of the non-Jew.

English

An Israelite who lent to a non-Jew on his Chametz, if he took it as a pledge in his hand and said to him: "from now," and the time arrived even after Pesach and he did not repay him, even if the responsibility for it does not fall upon him, it is forbidden, because he acquires it retroactively. But if he did not say to him: "from now," and the responsibility for it does not fall upon him, it is permitted: