Allah, exalted be His praise, said: "O you who believe! Fear Allah and give up what remains of usury (riba), if you are believers. And if you do not do so, then take notice of war from Allah and His Messenger. But if you repent, you shall have your principal sums; you shall neither wrong nor be wronged." [Surah al-Baqarah: 278-279]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / Q10464