if one of you invites his brother, he should accept(the invitation), whether it is a wedding feast or something of that nature.

قَالَ رَسُولُ اللَّهِ ﷺ إِذَا دَعَا أَحَدُكُمْ أَخَاهُ فَلْيُجِبْ عُرْسًا كَانَ أَوْ نَحْوَهُ