Musannaf Ibn Abi Shayba 13:2814

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Hammad ibn Salamah narrated to us, he said: I heard a sheikh who was called al-Mughirah, he said: I said to Ibn Umar, "I lend to my neighbors until the time of the stipend (al-‘ata’), and they pay me back in dirhams that are better than my dirhams." He said: "There is no harm in it, as long as you do not stipulate it."