Sahih al-Bukhari, Hadith 3546 ⓘ
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."
حَدَّثَنَا عِصَامُ بْنُ خَالِدٍ، حَدَّثَنَا حَرِيزُ بْنُ عُثْمَانَ، أَنَّهُ سَأَلَ عَبْدَ اللَّهِ بْنَ بُسْرٍ صَاحِبَ النَّبِيِّ صلى الله عليه وسلم قَالَ أَرَأَيْتَ النَّبِيَّ صلى الله عليه وسلم كَانَ شَيْخًا قَالَ كَانَ فِي عَنْفَقَتِهِ شَعَرَاتٌ بِيضٌ.
also referenced under: Book 61, Hadith 55 (In-Book) & Volume 4, Book 56, Hadith 746 (USC-MSA)