Musnad Ahmad 5:559

Abu Mu'awiyah narrated to us, Ibn Abi Layla narrated to us, from 'Amr ibn Murrah, from 'Abdullah ibn Salamah, from 'Ali, who said: "The Messenger of Allah, peace and blessings of Allah be upon him, would recite the Qur'an to us as long as he was not in a state of major ritual impurity (junub)."