Virtues and Merits of the Prophet (pbuh) and his Companions
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.Narrated Hariz bin `Uthman:That he asked `Abdullah bin Busr (i.e. the companion of the Prophet), "Did you see the Prophet (ﷺ) when he was old?" He said, "He had a few white hairs between the lower lip and the chin
From Sahih al-Bukhari, whose reports the scholars accept as authentic.