حَدَّثَنَا يَحْيَى، عَنِ ابْنِ أَبِي عَرُوبَةَ، حَدَّثَنَا قَتَادَةُ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ
قَالَ: قَالَ عُمَرُ رَضِيَ اللَّهُ عَنْهُ إِنَّ آخِرَ مَا نَزَلَ مِنْ الْقُرْآنِ آيَةُ الرِّبَا وَإِنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قُبِضَ وَلَمْ يُفَسِّرْهَا فَدَعُوا الرِّبَا وَالرِّيبَةَ
The last thing to be revealed was the verse on riba, but the Messenger of Allah (sallallahu alayhi wa sallam) passed away and did not discuss it with us. So give up riba and doubtful things.
Musnad Ahmad 237, Book 2, Musnad `Umar b. al-Khattab (ra), Hadith 160. 1 min read