Sunan Abi Dawud Book 35, Hadith 43
We used to grow beard long except during the Hajj or 'Umrah.
Abu Dawud said: Istihdad means to shave the pubes.
The Messenger of Allah (ﷺ) fixed forty days to shave the pubes, paring the nails, clipping the moustaches, and plucking the hair under the armpit.
Abu Dawud said: Ja'far b. Sulaiman transmitted it from Abu 'Imran on the authority of Anas. In this version he did not mention the Prophet (ﷺ). He said: Forty days were fixed for us. This is a more correct version.
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.