Musnad Ahmad 32:423

Sulayman ibn Harb narrated to us, Sulayman ibn al-Mughirah narrated to us, from Thabit, from Anas, who said: "I saw the Messenger of Allah, may Allah bless him and grant him peace, while the barber was shaving him, and his companions had surrounded him. They did not want a single hair to fall except into the hand of a man."