﴾وَقَالُوا قُلُوبُنَا غُلْفٌ﴿ “And they said, ‘Our hearts are wrapped.’”: The word Ghulf here means closed, contented and wrapped. They mean to say that in their hearts is knowledge that suffices them, such that they are not in need of new messages or laws. It can also mean that their hearts are wrapped and sealed, that is, Allah U has stamped and put a seal on their hearts such that the light of guidance cannot enter them, nor can the darkness of disbelief leave.
﴾بَلْ لَعَنَهُمْ اللَّهُ بِكُفْرِهِمْ فَقَلِيلاً مَا يُؤْمِنُونَ ﴿ “But, [in fact], Allah has cursed them for their disbelief, so little is it that they believe.”
According to the principle of (Preserving the Possibilities), Allah U acknowledges that they do have believe, though a little. Allah U did not totally deny belief from them, as among them, there are those who believed.