"Al-Bukhaari (5889) and Muslim (257) narrated from Abu Hurayrah (may Allah be pleased with him) that the Prophet (blessings and peace of Allah be upon him) said: “The fitrah is five things – or five things are part of the fitrah – circumcision, shaving the pubes, cutting the nails, plucking the armpit hairs, and trimming the moustache.”"
https://islamqa.info/en/answers/202827/the-wisdom-behind-the-prescription-to-remove-pubic-hair-and-armpit-hair