This is because they said, “The hellfire will not touch us, except for a few days.” They were thus deceived in their religion by their own fabrications.
ذٰلِكَ بِأَنَّهُم قالوا لَن تَمَسَّنَا النّارُ إِلّا أَيّامًا مَعدودٰتٍ وَغَرَّهُم فى دينِهِم ما كانوا يَفتَرونَ
zaalika bi annahum qaaloo lan tamassanan naaru illaaa ayyaamam ma’doodaatinw wa gharrahum fee deenihim maa kaanoo yaftaroon