Surah Al-Munafiqun (المنافقون) Ayah 3 - Tafsir

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."