صحيح مسلم

Anas b. Malik reported that Allah's Messenger (ﷺ) was neither very conspicuously tall nor short-statured, and his color was neither glaringly white nor brown; his hair was neither very curly nor very straight; Allah commissioned him (as a Prophet) when he had reached the age of forty years, and he stayed in Mecca for ten years and for ten years in Medina; Allah took him away when he had just reached the age of sixty, and there had not been twenty white hair in his head and beard.