Musannaf Ibn Abi Shayba 16:235

Abu Bakr narrated to us, he said: Ma'n ibn 'Isa narrated to us, from Muhammad ibn 'Abd Allah, the nephew of al-Zuhri, he said: My sister informed me that she saw al-Zuhri eating with five [fingers]. She asked him about that, and he said: The Prophet, may Allah bless him and grant him peace, used to eat with the five [fingers].