Sayyiduna Awf bin Malik (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Beware of the sins that are not forgiven: treachery with the spoils (ghulul), for whoever acts treacherously will come with it on the Day of Resurrection; and the consumer of usury (riba), for whoever consumes usury will be raised on the Day of Resurrection insane and staggering." Then he (peace and blessings be upon him) recited this verse: "Those who consume usury will not stand (on the Day of Resurrection) except as one stands whom Satan has driven to madness by his touch" [Al-Baqarah: 275].
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15201