Hadith 8:794
Abu Bakr narrated to us, he said: Hafs narrated to us, from Layth, from ‘Ata’, Tawus, and Mujahid, that they said: Regarding the one in the state of Ihram, if he plucks his armpit hair or clips his nails, then upon him is the expiation (fidyah).
حدثنا أبو بكر قال ثنا حفص عن ليث عن عطاء وطاوس ومجاهد أنهم قالوا في المحرم إذا نتف إبطه أو قلم أظفاره فإن عليه الفدية