Musnad Ahmad 32:1897

'Affan and Bahz narrated to us, they said: Hammam narrated to us, Qatadah narrated to us, from Anas: "The Prophet, may Allah bless him and grant him peace, his hair used to strike his shoulders." Bahz said: "Indeed, the Messenger of Allah, may Allah bless him and grant him peace, had hair that would strike his shoulders."