Musnad Ahmad 658:145

Aswad ibn Amir narrated to us, Isra'il informed us, Abu Ishaq narrated to us, and Yahya ibn Abi Bukayr narrated to us, Isra'il narrated to us, from Abu Ishaq, who said: I heard al-Bara' saying: "I have not seen anyone among the creation of Allah more handsome in a red garment than the Messenger of Allah, may Allah bless him and grant him peace, and his hair would strike his shoulders." Ibn Abi Bukayr said: "It would strike near his shoulders." "And I heard him narrate it repeatedly; he never narrated it without smiling."