(32) Chapters on Dress
كتاب اللباس
(35) Chapter: One who does not dye his hair
(35) باب مَنْ تَرَكَ الْخِضَابَ
Sunan Ibn Majah 3628 
It was narrated that Abu Juhaifah said:
“I saw the Messenger of Allah (ﷺ), and this part of his hair was white” – meaning the tuft of hair between the lower lip and the chin.
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا أَبُو دَاوُدَ، حَدَّثَنَا زُهَيْرٌ، عَنْ أَبِي إِسْحَاقَ، عَنْ أَبِي جُحَيْفَةَ، قَالَ رَأَيْتُ رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ هَذِهِ مِنْهُ بَيْضَاءُ ‏.‏ يَعْنِي عَنْفَقَتَهُ ‏.‏
Grade :  Sahih (Darussalam)
Reference : Sunan Ibn Majah 3628
In-book reference : Book 32, Hadith 79
English translation : Vol. 4, Book 32, Hadith 3628