عن أبى هريرة رضى الله عنه
قال: قال رسول الله صلى الله عليه وسلم: «إذا دعي أحدكم، فليجب، فإن كان صائما فليصل، وإن كان مفطراً فليطعم»
The Messenger of Allah (sallallahu alayhi wa sallam) said, “When any of you is invited to a meal, he should accept the invitation. If he is observing Saum (fasting), he should supplicate for the betterment of the host and if he is not fasting, he should eat.”.
Riyad as-Salihin 737, Book 3, The Book About the Etiquette of Eating, Hadith 11. 1 min read