Silsilat al-Ahadith al-Sahihah

Mukhawwil says: I heard Abu Sa‘d, a resident of Madinah, say: I saw Hasan performing prayer, and he had gathered and tied his hair on his head. The servant of the Messenger of Allah (peace and blessings be upon him), Abu Rafi‘, untied his hair or forbade him from doing so and said: The Messenger of Allah (peace and blessings be upon him) forbade that a man should perform prayer while his hair is gathered and tied at the back of his head.