Sunan Abi Dawud Book 35, Hadith 45
The Prophet (ﷺ) as saying: Jews and Christians do not dye (their beards), so act differently from them.
Do not pluck out grey hair. If any believer grows a grey hair in Islam, he will have light on the Day of Resurrection. (This is Sufyan's version). Yahya's version says: Allah will record on his behalf a good deed for it, and will blot out a sin for it.
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.