They were satisfied to be with those who stay behind, and their hearts were sealed over, so they do not understand.
رَضُوا بِأَنْ يَكُونُوا مَعَ الْخَوَالِفِ وَطُبِعَ عَلَىٰ قُلُوبِهِمْ فَهُمْ لَا يَفْقَهُونَ
They were satisfied to be with those who stay behind, and their hearts were sealed over, so they do not understand.
رَضُوا بِأَنْ يَكُونُوا مَعَ الْخَوَالِفِ وَطُبِعَ عَلَىٰ قُلُوبِهِمْ فَهُمْ لَا يَفْقَهُونَ
That is because they believed, and then they disbelieved; so their hearts were sealed over, and they do not understand.
ذَٰلِكَ بِأَنَّهُمْ آمَنُوا ثُمَّ كَفَرُوا فَطُبِعَ عَلَىٰ قُلُوبِهِمْ فَهُمْ لَا يَفْقَهُونَ