Sahih Al-Bukhari Hadith 7.779 Narrated by Abu Huraira
I heard the Prophet (saws) saying. "Five practices are characteristics of the
‘Fitra’ (nature): removing the pubic hair, clipping the nails, depilating the hair
of the armpits; and circumcision and cutting the moustaches short (for the males)
Anas ibn Malik (r.a.) reported "The time period for us to trim the moustache, clip
the nails, pluck out the underarm hairs and cut the pubic hairs was (once in at
least) forty nights."
Related by Ahmad and Abu Dawud.