عَن ثابتٍ قَالَ: سُئِلَ أَنَسٌ عَنْ خِضَابِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَقَالَ: لَوْ شِئْتَ أَنْ أَعُدَّ شَمَطَاتٍ كُنَّ فِي رَأْسِهِ فَعَلْتُ قَالَ: وَلَمْ يَخْتَضِبْ زَادَ فِي رِوَايَةٍ: وَقَدِ اخْتَضَبَ أَبُو بَكْرٍ بِالْحِنَّاءِ وَالْكَتَمِ وَاخْتَضَبَ عُمَرُ بِالْحِنَّاءِ بحتا

Thabit told that when Anas was asked whether the Prophet dyed his hair he replied, "If I had wanted to count the hoary hairs which were on his head I could have done so,” adding that he did not dye his hair. In a version he added that Abu Bakr dyed his hair with henna and katam, and ‘Umar dyed it with henna alone. (Bukhari and Muslim.)