Example in the Quran

أَوَكُلَّمَا عَٰهَدُواْ عَهۡدٗا نَّبَذَهُۥ فَرِيقٞ مِّنۡهُمۚ بَلۡ أَكۡثَرُهُمۡ لَا يُؤۡمِنُونَ

Why is it that every time they make a covenant, a group of them casts it aside? In fact, most of them do not believe.