´Narrated Anas bin Malik:` "[The Messenger of Allah (ﷺ)] fixed the time for us paring the mustache, trimming the fingernails, shaving the pubic hairs and plucking the underarm hairs - that we not leave it for more than forty days."
Hadith ReferenceSunan at-Tirmidhi / Chapters on Manners / Hadith: 2759