The Messenger of Allah ﷺ said, "When the servant of one of you has prepared food, having borne its heat and its toil, let him invite the servant to sit and eat with him. If he does not invite him, let him at least hand him a portion of it."
وإذا صنع خادم أحدكم طعاما فولي حره ومشقته فليدعه فليأكل معه فإن لم يدعه فليناوله منه
No references are available.
Its chain of transmission is sahih. As for its first part, it is found in Bukhari 8/175, in the book of seeking permission, chapter "A man should not make another man stand up," and in Muslim 4/1714, number 2177, in the book of greetings, chapter on the prohibition of making a person get up from his place. As for the second part, it has already appeared at 9278, and the third has already appeared at 9889.