Musnad Ahmad 25:1140

Yahya ibn Adam narrated to us, Isra'il narrated to us, from Ibrahim ibn Muhajir, from Mujahid, from Ibn Abbas, who said: "The Prophet, may Allah bless him and grant him peace, used to present the Quran to Gabriel once every year. When the year in which he passed away arrived, he presented it to him twice." And the recitation of Abdullah was the final recitation.