Musnad Abu Ya'la al-Mawsili 115:6

Shayban ibn Farrukh narrated to us, Jarir ibn Hazim narrated to us, Qatadah narrated to us, he said: I said to Anas, "How was the hair of the Messenger of Allah, may Allah bless him and grant him peace?" He said, "It was wavy hair, neither curly nor straight, [reaching] between his earlobes and his shoulders."