Musnad Abu Ya'la al-Mawsili 109:228

Abu Khaythama narrated to us, Sa'id bin 'Amir narrated to us, from Shu'bah, from Makhul, from Muhammad bin 'Ali, from Jabir bin 'Abdullah, who said: When the Messenger of Allah (may Allah bless him and grant him peace) performed ghusl (ritual bath), he would pour three [handfuls/vessels] over his head. A man from Banu Hashim said, "Indeed, my hair is thick." He (the Prophet) said, "The hair of the Messenger of Allah (may Allah bless him and grant him peace) was thicker than your hair, and better."