Hadith 1266

Umm 'Umarah Al-Ansariyah (May Allah be pleased with her) reported: Once the Prophet (PBUH) visited us and I served him some food. He (PBUH) asked me to eat. I replied that I was observing (optional) fast. He (PBUH) said, "When people eat by a person observing fast, the angels keep asking Allah's forgiveness for that person until they have had their fill."

[At-Tirmidhi].