فَبِما نَقضِهِم ميثاقَهُم وَكُفرِهِم بِآياتِ اللَّهِ وَقَتلِهِمُ الأَنبِياءَ بِغَيرِ حَقٍّ وَقَولِهِم قُلوبُنا غُلفٌ ۚ بَل طَبَعَ اللَّهُ عَلَيها بِكُفرِهِم فَلا يُؤمِنونَ إِلّا قَليلًا

Yet, they broke their pledge, denied God’s revelations, unjustly killed the prophets, and said, “Our hearts are sealed.” God sealed them due to their disbelief, so they believe only a little.