Sahih Muslim Book 8, Hadith Number 3346.

Chapter: When one is invited to a wedding feast, one should accept it.

Jabir (Allah be pleased with him) reported that Allah’s Messenger (may peace he upon him) said: When any one of you is invited to a feast, he should accept it. He may eat if he likes, or he may abandon (eating) if he likes. Ibn Mathanni did not make mention of the word “feast”.