Musnad Abu Ya'la al-Mawsili 42:253

Zuhayr narrated to us, Yahya bin Sa'id narrated to us, from al-Taymi, from Abu Nadra, from Abu Sa'id: That a man came to the Prophet, may Allah bless him and grant him peace, with dates that he disapproved of. He said, "Where did you get this from?" He said, "I took it for two sa's of dates." He said, "You have doubled and practiced usury (riba), or you have practiced usury and doubled."