He informed them of this from the Prophet ﷺ, who said, "When the servant of one of you has spared him the heat and smoke of preparing his food, let him take his hand and seat him with him to eat. If he refuses, let him take a morsel and feed it to him."
حدثنا نصر بن علي حدثنا سفيان عن إسمعيل بن أبي خالد عن أبيه
يخبرهم ذاك عن النبي ﷺ قال إذا كفى أحدكم خادمه طعامه حره ودخانه فليأخذ بيده فليقعده معه فإن أبى فليأخذ لقمة فليطعمها إياه
[Sahih]. Ibn Majah also narrated it in the Book of Foods, chapter "If his servant brings him his food, he should give him some of it," hadith no. 3289, from the hadith of Ismail bin Abu Khalid, through the same route, but its chain is daif because of Ismail's use of "an" (indicating a possible break in transmission). However, the hadith has many corroborating narrations in Bukhari, Muslim, Ibn Majah (3290), and others.