Musnad Ahmad 27:1724

Ya'qub narrated to us, 'Asim ibn Muhammad narrated to us, from his brother 'Umar ibn Muhammad, from al-Qasim ibn 'Ubayd Allah ibn 'Abd Allah ibn 'Umar, [who said]: I heard Salim say: 'Abd Allah ibn 'Umar said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Let not one of you eat with his left hand, and let him not drink with it, for indeed, the devil eats with his left hand and drinks with it."