Musnad Abu Ya'la al-Mawsili 115:270

Zuhayr narrated to us, Shababah ibn Sawwar narrated to us, al-Mughirah ibn Muslim narrated to us, from Matar, from Qatadah, from Anas, who said: The Messenger of Allah (may Allah bless him and grant him peace) forbade drinking while standing and eating while standing.