Musannaf Ibn Abi Shayba 13:1072

Abu Bakr narrated to us, he said: Humayd ibn Abd al-Rahman al-Ru'asi narrated to us, from Dinar, who said: I asked al-Hasan: "I give a dirham to a money changer in Basra and I take a *suftaja* (bill of exchange), and I take the equivalent of my dirhams in Kufa." He said: "This is only done because of the thieves. There is no good in a loan that brings a benefit."