The Prophet (ﷺ) said: The best things with which grey hair are changed are henna and katam.
Sunan Abi Dawud Book 35, Hadith 47
← Previous Hadith Abu Quhafah was brought on the day of the conquest of Mecca with head and beard while like hyssop. The Messenger of Allah (ﷺ) said: Change this something, but avoid black.

Sunan Abi Dawud Book 35, Hadith 46 Next Hadith → I went with my father to the Prophet (ﷺ). He had locks hanging down as far as the lobes of the ears stained with henna, and he was wearing two green garments.

Sunan Abi Dawud Book 35, Hadith 48