Musnad Abu Ya'la al-Mawsili 115:325

Abu Khaythama narrated to us, Ibn Abi Adi narrated to us, from Sa’id, from Qatada, from Anas, from the Prophet (may Allah bless him and grant him peace): That he forbade a man from drinking while standing. Qatada said: So we said, "What about eating?" He said: "That is worse, or more evil."