Sahih Muslim Book 30, Hadith Number 5713.

Chapter : The angels fought along with Allah’s Apostle (may peace be upon him) in the Battle of Uhud.

Sa’d reported that on the Day of Ubud I saw on the right side of Allah’s Messenger (may peace be upon him) and on his left side two persons dressed in white clothes and whom I did not see before nor after that, and they were Gabriel and Michael (Allah be pleased with both of them).