The Book of Purification
1/11. Chapter:
Plucking The Armpit Hairs
Sunan an-Nasai
أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ يَزِيدَ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنِ الزُّهْرِيِّ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " خَمْسٌ مِنَ الْفِطْرَةِ الْخِتَانُ وَحَلْقُ الْعَانَةِ وَنَتْفُ الإِبْطِ وَتَقْلِيمُ الأَظْفَارِ وَأَخْذُ الشَّارِبِ " .
It was narrated from Abu Hurairah that the Prophet (ﷺ) said: "The Fitrah are five: Circumcision, shaving the pubes, plucking the armpit hairs, clipping the nails and taking from the mustache."
Reference : Sunan an-Nasa'i 11In-book reference : Book 1, Hadith 11English translation : Vol. 1, Book 1, Hadith 11