Musnad Ahmad 32:235

Waki’ and Bahz narrated to us, they said: Hammam narrated to us, from Qatadah, who said—and Bahz said in his narration: Qatadah informed us—from Anas, who said: "The Messenger of Allah, peace and blessings of Allah be upon him, had hair that would reach his shoulders." And Bahz said: "It would strike his shoulders."