Jami` at-Tirmidhi 1753
جامع الترمذي#1753SahihNarrated Abu Dharr: That the Prophet (ﷺ) said: "Indeed the best of what the gray may be changed with is Henna' and Katam." [Abu 'Eisa said:] This Hadith is Hasan Sahih. Abu Al-Aswad Ad-Dili's (a narrator in this chain) name is Zalim bin 'Amr bin Sufyan
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiSahih
In-book reference: 24:34