The Messenger of Allah ﷺ said, "When one of you has his servant bring him food, after the servant has spared him its trouble and its heat, let him invite the servant to eat with him. If he does not do so, let him take a morsel and place it in the servant's hand."
حدثنا عيسى بن حماد المصري أنبأنا الليث بن سعد عن جعفر بن ربيعة عن عبد الرحمن الأعرج
قال رسول الله ﷺ إذا أحدكم قرب إليه مملوكه طعاما قد كفاه عناءه وحره فليدعه فليأكل معه فإن لم يفعل فليأخذ لقمة فليجعلها في يده
No references are available.
[Its isnad is sahih] * Jafar bin Rabia was corroborated by Abu Zinad, as recorded by Ahmad: 2/245, and the hadith has other routes of transmission recorded by Bukhari and Muslim and others.