It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that whenever food was brought to the Prophet (peace and blessings be upon him), if it was said, "It is a gift," he (peace and blessings be upon him) would also eat; and if it was said, "It is charity," he (peace and blessings be upon him) would not eat.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الهبات / 12048