(1) باب الْفِطْرَةِ
It was narrated that Talq bin Habib said:
"Ten things are from the Sunnah: Using the Siwak, trimming the mustache, rinsing the mouth, rinsing the nose, letting the beard grow, trimming the nails, plucking the armpit hairs, circumcision, shaving the pubes and washing one's backside."
Reference: Sunan an-Nasa'i 5042
In-book reference: Book 48, Hadith 3
English translation: Vol. 6, Book 48, Hadith 5045