Hubayrah bin Yarim said that Sayyiduna al-Hasan bin Ali (may Allah be pleased with him) said: "The Messenger of Allah (peace and blessings be upon him) used to send him - that is, Sayyiduna Ali (may Allah be pleased with him) - with the army detachment, and he would fight, with Jibril on his right and Mika'il on his left, and he would not return until Allah granted him victory."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2705