Sunan Abi Dawud 4205
سنن أبي داود#4205SahihNarrated AbuDharr: The Prophet (ﷺ) said: The best things with which grey hair are changed are henna and katam
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Zubair Ali ZaiIsnaad Sahih
In-book reference: 35:47