Sahih Muslim , Book 30, Hadith 5794 (USC-MSA) ⓘ

Anas b. Malik reported that Allah's Messenger 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.

حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ رَبِيعَةَ بْنِ أَبِي عَبْدِ الرَّحْمَنِ، عَنْ أَنَسِ بْنِ مَالِكٍ، أَنَّهُ سَمِعَهُ يَقُولُ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم لَيْسَ بِالطَّوِيلِ الْبَائِنِ وَلاَ بِالْقَصِيرِ وَلَيْسَ بِالأَبْيَضِ الأَمْهَقِ وَلاَ بِالآدَمِ وَلاَ بِالْجَعْدِ الْقَطَطِ وَلاَ بِالسَّبِطِ بَعَثَهُ اللَّهُ عَلَى رَأْسِ أَرْبَعِينَ سَنَةً فَأَقَامَ بِمَكَّةَ عَشْرَ سِنِينَ وَبِالْمَدِينَةِ عَشْرَ سِنِينَ وَتَوَفَّاهُ اللَّهُ عَلَى رَأْسِ سِتِّينَ سَنَةً وَلَيْسَ فِي رَأْسِهِ وَلِحْيَتِهِ عِشْرُونَ شَعْرَةً بَيْضَاءَ ‏.‏