Musnad Ahmad 27:90

Sufyan narrated to us, from al-Zuhri, Abu Bakr ibn Ubayd Allah ibn Umar narrated to me, from his grandfather, from the Prophet, peace and blessings of Allah be upon him, who said: "If one of you eats, let him eat with his right hand, and if he drinks, let him drink with his right hand, for the devil eats with his left hand and drinks with his left hand."