Musnad Ahmad 33:858

Sa'id ibn 'Amir narrated to us, Shu'bah said: We were informed by Makhul, from Abu Ja'far Muhammad ibn 'Ali ibn al-Husayn, from Jabir: "That the Messenger of Allah, peace and blessings of Allah be upon him, when he performed ghusl (ritual bath), he would pour three [handfuls/vessels] over his head." He said: A man from Banu Hashim said, "My hair is thick." Jabir said: "The hair of the Messenger of Allah, peace and blessings of Allah be upon him, was thicker than your hair and better."