Thabit said that Anas was asked about the hair-dye of the Prophet (ﷺ). He replied:

He did not dye his hair, but Abu Bakr and 'Umar dyed their hair.

حَدَّثَنَا مُحَمَّدُ بْنُ عُبَيْدٍ، حَدَّثَنَا حَمَّادٌ، عَنْ ثَابِتٍ، عَنْ أَنَسٍ، أَنَّهُ سُئِلَ عَنْ خِضَابِ النَّبِيِّ، صلى الله عليه وسلم فَذَكَرَ أَنَّهُ لَمْ يَخْضِبْ وَلَكِنْ قَدْ خَضَبَ أَبُو بَكْرٍ وَعُمَرُ رَضِيَ اللَّهُ عَنْهُمَا ‏.‏