It is reported from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "When a slave prepares food for his master, the master should have him eat with him; if he does not eat, let him at least set aside a morsel or two for him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النفقات / 15782