Musnad Ahmad 26:190

'Abd al-Razzaq narrated to us, Isra'il informed us, from Simak, from 'Abd al-Rahman ibn 'Abd Allah, from Ibn Mas'ud, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) cursed the consumer of usury, the one who pays it, its two witnesses, and its scribe."