Musnad Ahmad 534:10

Abu al-Mughirah narrated to us, Hariz narrated to us, he said: I asked Abdullah ibn Busr al-Mazini, a companion of the Messenger of Allah, may Allah bless him and grant him peace, and I said: "Did you see the Prophet, may Allah bless him and grant him peace? Was he an old man?" He said: "There were some white hairs in his *'anfaqah* (the hair between the lower lip and the chin)."