Sahih Muslim 1429
Sahih Muslim · Book 16: The Book of Marriage · The command to accept invitations
Ibn Umar (Allah be pleased with them) reported Allah's Apostle (ﷺ) having said:
وَحَدَّثَنِي حَرْمَلَةُ بْنُ يَحْيَى ، أَخْبَرَنَا ابْنُ وَهْبٍ ، حَدَّثَنِي عُمَرُ بْنُ مُحَمَّدٍ ، عَنْ نَافِعٍ ، عَنِ ابْنِ عُمَرَ ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " إِذَا دُعِيتُمْ إِلَى كُرَاعٍ فَأَجِيبُوا " .
When you are invited to a feast (even though it is) the leg of the sheep, you should accept it.