Example in the Quran

وَقَالُواْ قُلُوبُنَا غُلۡفُۢۚ بَل لَّعَنَهُمُ ٱللَّهُ بِكُفۡرِهِمۡ فَقَلِيلٗا مَّا يُؤۡمِنُونَ

They say, “Our hearts are unreceptive!” In fact, Allah has condemned them for their disbelief. They have but little faith.