Chapter 35: Combing the Hair (Kitab Al-Tarajjul)
' Amr b. Shu' aib, on his father' s authority, told that his grandfather reported the Messenger of Allah (ﷺ) said: 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.
Sunan Abi Dawud 4202