I saw the Messenger of Allah ﷺ, and this part of him was white, meaning the hair between his lower lip and chin.
حدثنا محمد بن المثنى حدثنا أبو داود حدثنا زهير عن أبي إسحق
رأيت رسول الله ﷺ هذه منه بيضاء يعني عنفقته
Bukhari narrated it in the Book of Virtues, Chapter on the Description of the Prophet ﷺ, no. 3545, from the hadith of Abu Ishaq through this route, and Muslim narrated it in the Book of Virtues, Chapter on his grey hair, no. 2342, from the hadith of Zuhayr through this route. It is also found in Musnad Abu Dawud Tayalisi, no. 1046, in a longer form than this.