Musnad Abu Ya'la al-Mawsili 108:82

Zuhayr narrated to us, Hushaym ibn Bashir narrated to us, Abu al-Zubayr narrated to us, from Jabir, who said: The Messenger of Allah (may Allah bless him and grant him peace) cursed the consumer of usury, the one who pays it, its scribe, and its two witnesses. And he said: "They are equal."