Musnad Ahmad 25:1151

Muhammad ibn Ubayd narrated to us, Muhammad ibn Ishaq narrated to us, from Ibn Shihab, from Ubayd Allah ibn Abdullah ibn Utbah, from Ibn Abbas, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) used to present the Quran every Ramadan to Gabriel. So the Messenger of Allah (peace and blessings of Allah be upon him) would become, from the night in which he presented what he presented, more generous than the sent wind; he would not be asked for anything except that he gave it. Until it was the month in which he died, he presented it twice."