The last thing revealed from the Quran was "And fear a Day when you will be returned to Allah" [Baqarah 2:281].
آخر شيء نزل من القرآن: {واتقوا يوما ترجعون فيه إلى الله}
Nasai narrated it in Kubra (10/39-40), from Husayn bin Hurayth, who reported, "Fadl bin Musa informed us, from Husayn bin Waqid, from Yazid, from Ikrima, from Ibn Abbas," and he related it. Its chain is hasan because of Husayn bin Waqid.