Sunan Ibn Majah 1042

Mukhawwal said:“I heard Abu Sa’d, a man from the people of Madinah, say: ‘I saw Abu Rafi’, the freed slave of the Messenger of Allah (ﷺ), when he saw Hasan bin ‘Ali performing prayer, with his hair braided. He undid it, or told him not to do that, and said: “The Messenger of Allah (ﷺ) forbade a man from performing prayer with his hair braided.”