Sunan an-Nasa'i, Volume 6, Book 48, Hadith 5081 (DarusSalam) ⓘ
It was narrated that Abu Dharr said: "The Messenger of Allah [SAW] said: 'The best things with which you can change gray hair are Henna and Katam.'"
أَخْبَرَنَا يَعْقُوبُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنِ الأَجْلَحِ، عَنْ عَبْدِ اللَّهِ بْنِ بُرَيْدَةَ، عَنْ أَبِي الأَسْوَدِ الدِّيلِيِّ، عَنْ أَبِي ذَرٍّ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِنَّ أَحْسَنَ مَا غَيَّرْتُمْ بِهِ الشَّيْبَ الْحِنَّاءُ وَالْكَتَمُ " .
also referenced under: Hadith 5078 (Reference) & Book 48, Hadith 39 (In-Book)