Verse 155

فَبِمَا نَقْضِهِم مِّيثَـٰقَهُمْ وَكُفْرِهِم بِـَٔايَـٰتِ ٱللَّهِ وَقَتْلِهِمُ ٱلْأَنۢبِيَآءَ بِغَيْرِ حَقٍّ وَقَوْلِهِمْ قُلُوبُنَا غُلْفٌۢ بَلْ طَبَعَ ٱللَّهُ عَلَيْهَا بِكُفْرِهِمْ فَلَا يُؤْمِنُونَ إِلَّا قَلِيلًا

Thereafter, they broke their covenant because of their disbelief in God’s proofs and their killing of the prophets unjustly and because of their utterance that our hearts are shielded. However, it is God who sealed them because of their disbelief; therefore, they can never attain faith except a few.