"I heard the Prophet [SAW] say: 'Some of the best things with which you can change gray hair are Henna and Katam.'" (Using translation from Nasāʾī 5079)
سَمِعْتُ النَّبِيَّ ﷺ يَقُولُ «إِنَّ مِنْ أَحْسَنِ مَا غُيِّرَ بِهِ الشَّيْبُ الْحِنَّاءُ وَالْكَتَمُ» خَالَفَهُ الْجُرَيْرِيُّ وَكَهْمَسٌ