Musnad Ahmad 33:613

Musa narrated to us, Ibn Lahi'ah narrated to us, from Abu al-Zubayr, that he asked Jabir about a man’s servant, when he spares him the hardship and the heat. He said: "The Prophet, may Allah bless him and grant him peace, commanded us to invite him. If one of us dislikes to eat with him, then let him feed him a morsel in his hand."