Sahih al-Bukhari 5895

Arabic

حَدَّثَنَا سُلَيْمَانُ بْنُ حَرْبٍ، حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ ثَابِتٍ، قَالَ سُئِلَ أَنَسٌ عَنْ خِضَابِ النَّبِيِّ، صلى الله عليه وسلم فَقَالَ إِنَّهُ لَمْ يَبْلُغْ مَا يَخْضِبُ، لَوْ شِئْتُ أَنْ أَعُدَّ شَمَطَاتِهِ فِي لِحْيَتِهِ‏.‏

English translation

Narrated Thabit:Anas was asked whether the Prophet (ﷺ) used a a hair dye or not. He replied, "The Prophet (ﷺ) did not have enough grey hair to dye, (such that) if I wanted to count the fading hairs in his beard (I could have)

Reference: Sahih al-Bukhari 5895, Book of Dress. English translation by Dr. Muhammad Muhsin Khan.