Musnad Ahmad 30:2068

Yahya ibn Ishaq narrated to us, Abu Bakr—meaning Ibn Ayyash—narrated to us, he said: Abu Husayn narrated to us, from Abu Salih, from Abu Hurayrah, who said: "The Qur'an used to be presented to the Prophet, may Allah bless him and grant him peace, once every year. When it was the year in which he passed away, it was presented to him twice."