Musannaf Ibn Abi Shayba 22:378

Ya'la ibn 'Ubayd narrated to us, from Muhammad ibn Ishaq, from al-Zuhri, from 'Ubayd Allah ibn 'Abd Allah, from Ibn 'Abbas, who said: The Messenger of Allah (may Allah bless him and grant him peace) used to present the Book [the Quran] in every Ramadan to Gabriel. When it was the month in which he passed away, he presented it to him twice.