(23) باب صِفَةِ النَّبِيِّ صلى الله عليه وسلم
Narrated Anas:
Allah's Messenger (ﷺ) was neither very tall nor short, neither absolutely white nor deep brown. His hair was neither curly nor lank. Allah sent him (as an Apostle) when he was forty years old. Afterwards he resided in Mecca for ten years and in Medina for ten more years. When Allah took him unto Him, there was scarcely twenty white hairs in his head and beard.
Reference: Sahih al-Bukhari 3548
In-book reference: Book 61, Hadith 57
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 56, Hadith 748