Musnad Abu Ya'la al-Mawsili 148:22

Muhammad ibn Isma'il ibn Abi Samina narrated to us, 'Abd al-A'la narrated to us, Hisham ibn Hassan narrated to us, from 'Abd Allah ibn Dihqan, from Anas ibn Malik: That the Messenger of Allah (may Allah bless him and grant him peace) forbade that a man should eat with his left hand or drink with his left hand.