Musnad Ahmad 5:783

Abdullah narrated to us, Suwayd ibn Sa'id narrated to me, Marwan al-Fazari narrated to us, from al-Mukhtar ibn Nafi', Abu Matar al-Basri narrated to me—and he had met Ali, may Allah be pleased with him—that Ali bought a garment for three dirhams. When he put it on, he said: "Praise be to Allah who has provided me with clothing with which I may adorn myself among the people and with which I may cover my nakedness." Then he said: "This is how I heard the Messenger of Allah, may Allah bless him and grant him peace, say."