Musnad Abu Ya'la al-Mawsili 151:15

Bishr ibn al-Walid al-Kindi narrated to us, Sharik narrated to us, from Simak, from Abd al-Rahman ibn Abd Allah ibn Mas'ud, from his father, from the Prophet (peace and blessings of Allah be upon him), who said: "Allah has cursed the consumer of usury, the one who pays it, its two witnesses, and its scribe." And he said: "Usury and adultery do not appear among a people except that they have made the punishment of Allah lawful upon themselves."