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.'" (FR)
English reference (FR): Vol. 1, Book 1, Hadith 292 (FR)
Arabic reference (FR): Book 1, Hadith 307 (FR)