Sunan Ibn Majah
3629
Sahih+3

It was narrated that Humaid said:“Anas bin Malik was asked: ‘Did the Messenger of Allah (ﷺ) dye his hair?’ He said: ‘He did not have any white hair apart from approximately seventeen or twenty hairs at the front of his beard.’”

SahihAl-Albani
SahihMuhammad Fouad Abd al-Baqi