אִם־אָ֣וֶן בְּ֭יָדְךָ הַרְחִיקֵ֑הוּ וְאַל־תַּשְׁכֵּ֖ן בְּאֹהָלֶ֣יךָ עַוְלָֽה׃
Если беззаконие будет в твоей руке, убери его далеко, и пусть неправедность не пребывает в твоих шатрах—
Kitzur Shulchan Arukh
It is forbidden to keep a paid note in your possession, for it is said,18Job 11:14. "Do not let unrighteousness dwell in your tents."19If it is partially repaid, Shulchan Aruch 57:1 says you must write a receipt for the amount paid. Shach 57:6 argues that even if you do not write a receipt for that part, you may keep the document until it is fully paid.