It was narrated that Abu Hurairah said:
"The Messenger of Allah said: 'The deeds connected to the Fitrah are five (or five things are connected to the Fitrah): circumcision, shaving the pubic hairs, clipping the nails, plucking the armpit hairs and trimming the mustache.'" (TR)
English reference (TR): Vol. 1, Book 1, Hadith 292 (TR)
Arabic reference (TR): Book 1, Hadith 307 (TR)