Mishkat al-Masabih

‘Amr b. Shu'aib, on his father’s authority, told that his grandfather reported God’s messenger as saying. “Do not pluck out grey hairs, for they are the Muslim’s light. If anyone grows a grey hair in Islam God will record on his behalf a good deed for it, will blot out a sin for it, and raise him a degree for it.” Abu Dawud transmitted it.