وَلِمُسْلِمٍ : { إِذَا دَعَا أَحَدُكُمْ أَخَاهُ , فَلْيُجِبْ; عُرْسًا كَانَ أَوْ نَحْوَهُ } 1 .1 - مسلم برقم (1429) (100).
Translation
Muslims has
"When one of you invites his brother, he must respond (i.e. attend), whether it is a wedding or something similar."