Musannaf Ibn Abi Shayba 13:2558

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Jarir ibn Hazim narrated to us, from Muhammad ibn Abi Ya’qub, from Yahya al-Tawil, he said: Ali was asked about *al-sarf* (currency exchange), and he said: "That is the hasty usury."