Divine wisdom in distinguishing believers from hypocrites

وَلَئِنْ أَصَـٰبَكُمْ فَضْلٌ مِّنَ ٱللَّهِ لَيَقُولَنَّ كَأَن لَّمْ تَكُنۢ بَيْنَكُمْ وَبَيْنَهُۥ مَوَدَّةٌ يَـٰلَيْتَنِى كُنتُ مَعَهُمْ فَأَفُوزَ فَوْزًا عَظِيمًا

But if bounty comes to you from Allāh, he will surely say, as if [i.e., showing that] there had never been between you and him any affection, "Oh, I wish I had been with them so I could have attained a great attainment."

رَضُوا۟ بِأَن يَكُونُوا۟ مَعَ ٱلْخَوَالِفِ 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.