It is narrated from Sayyiduna Abu Juhaifah (may Allah be pleased with him), he says that the Messenger of Allah (peace and blessings be upon him) said: "I do not eat while reclining."
Hadith Referenceشمائل ترمذي / باب ما جاء فى صفة أكل رسول الله صلى الله عليه وسلم / 138