Musnad Abu Ya'la al-Mawsili 42:332

Abu Khaythama narrated to us, Muhammad ibn Khazim narrated to us, from al-A'mash, from Sa'd al-Ta'i, from 'Atiyyah al-'Awfi, from Abu Sa'id, who said: The Messenger of Allah (may Allah bless him and grant him peace) mentioned the companion of the Trumpet and said: "On his right is Jibril, and on his left is Mika'il."