Qur'ān 63:3 · Al-Munafiqun (المنافقون)

ذَٰلِكَ بِأَنَّهُمْ ءَامَنُوا۟ ثُمَّ كَفَرُوا۟ فَطُبِعَ 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.