Sunan At-Tirmidhi

Narrated 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