(1) باب الْفِطْرَةِ
It was narrated that Abu Hurairah said:
"The Messenger of Allah [SAW] said: 'Five things are of the Fitrah: Circumcision, shaving the pubes, plucking the armpit hair, clipping the nails and trimming the mustache.'"
Reference: Sunan an-Nasa'i 5043
In-book reference: Book 48, Hadith 4
English translation: Vol. 6, Book 48, Hadith 5046