Qatada reports that he said:

‘I said to Anas ibn Malik: “Did Allah’s Messenger (ﷺ) dye his hair?” He replied: ‘He did not get to that, for he was grayed only in the hair covering his temples, but Abu Bakr (may Allah the Exalted be well pleased with him) dyed his hair with henna and a herbal mixture called katam.”

حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ، قَالَ‏:‏ أَخْبَرَنَا أَبُو دَاوُدَ، قَالَ‏:‏ أَخْبَرَنَا هَمَّامٌ، عَنْ قَتَادَةَ، قَالَ‏:‏ قُلْتُ لأَنَسِ بْنِ مَالِكٍ‏:‏ هَلْ خَضَبَ رَسُولُ اللهِ صلى الله عليه وسلم‏؟‏ قَالَ‏:‏ لَمْ يَبْلُغْ ذَلِكَ، إِنَّمَا كَانَ شَيْبًا فِي صُدْغَيْهِ وَلَكِنْ أَبُو بَكْرٍ، خَضَبَ بِالْحِنَّاءِ وَالْكَتَمِ‏.‏