Musannaf Ibn Abi Shayba 16:866

Abu Bakr narrated to us, he said: Mu'awiyah ibn Hisham and Sufyan ibn 'Uqbah narrated to us, from Sufyan, from 'Asim, from his father, from Wa'il ibn Hujr, who said: The Prophet, may Allah bless him and grant him peace, forbade me while I had long hair, and he said: "A fly, a fly." So I went and cut it off. Then the Prophet, may Allah bless him and grant him peace, saw me and said: "I did not mean you, and this is better."