Musnad Ahmad 26:133

Ammar ibn Muhammad narrated to us, from al-Hajari, from Abu al-Ahwas, from Abdullah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "When the servant of one of you brings his food, let him begin by letting him eat, or let him seat him with him, for he is the one who took care of its heat and its smoke."