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)."
عَنْ خِضَابِ النَّبِيِّ ﷺ فَقَالَ إِنَّهُ لَمْ يَبْلُغْ مَا يَخْضِبُ لَوْ شِئْتُ أَنْ أَعُدَّ شَمَطَاتِهِ فِي لِحْيَتِهِ