Chapter 35: Combing the Hair (Kitab Al-Tarajjul)
Narrated Al-Bara': I did not see any man with locks hanging down to shoulders in red robe more beautiful than the Messenger of Allah (ﷺ). Muhammad b. Sulaiman added: He had hair which touched his shoulders. Abu Dawud said: Isra' il also transmitted it in a similar way from Abu Ishaq saying: "(his hair) touched his shoulders". Shu' bah added: (His hair) reached the lobes of his ears.
Sunan Abi Dawud 4183