Musnad Ahmad 32:559

Yunus narrated to us, Abd al-Aziz—meaning Ibn Abd Allah ibn Abi Salamah—narrated to us, from Rabi'ah ibn Abi Abd al-Rahman, from Anas ibn Malik, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) passed away, and there were not twenty white hairs on his head and his beard."