Musnad Ahmad 30:2184

Muhammad ibn Ja'far narrated to us, he said: Shu'bah narrated to us, from Muhammad ibn Ziyad, he said: I heard Abu Hurairah saying: The Messenger of Allah, may Allah bless him and grant him peace, said: "When the servant of one of you brings his food to him, if he does not let him sit with him, then let him hand him a morsel or two morsels — or a bite or two bites, Shu'bah was in doubt — for he is the one who handled its preparation and its heat."