Yunus ibn Abdul ‘Ala reported: Ientered the home of Al-Shafi’i, may Allah have mercy on him, and with him was a barber shaving his armpits. Al-Shafi’i said, “I know the Sunnah is to pluck them, but I am not strong enough to endure the pain.”
Source: Sharḥ al-Nawawī ‘alá Ṣaḥīḥ Muslim 257