It was narrated that 'Umar bin Khattab said:
"The last thing to be revealed was the Verse on usury but the Messenger of Allah (ﷺ) died before he had explained it to us. So give up usury (interest) and doubtful things."
English reference: Vol. 3, Book 12, Hadith 2276
Arabic reference: Book 12, Hadith 2362