Sahih Bukhari – Hadith No : 3586

Narrated Hariz bin `Uthman: That he asked `Abdullah bin Busr (i.e. the companion of the Prophet), “Did you see the Prophet when he was old?” He said, “He had a few white hairs between the lower lip and the chin.”

Hadith In Arabic Text :

حدثنا عصام بن خالد، حدثنا حريز بن عثمان، أنه سأل عبد الله بن بسر صاحب النبي صلى الله عليه وسلم قال أرأيت النبي صلى الله عليه وسلم كان شيخا قال كان في عنفقته شعرات بيض‏.‏

Chapter : Virtues and Merits of the Prophet (pbuh) and his Companions – كتاب المناقب