Musnad Abu Ya'la al-Mawsili 3:80

Ubayd Allah narrated to us, Muhammad ibn Abd Allah ibn al-Zubayr narrated to us, Mis'ar narrated to us, from Abu 'Awn, from Abu Salih al-Hanafi, from Ali, who said: The Messenger of Allah (ﷺ) said to me on the day of Badr, and to Abu Bakr: "With one of you is Gabriel, and with the other is Michael, and Israfil is a mighty angel who witnesses the battle, or he is in the battle."