فَكَذَّبُوهُ فَأَخَذَهُمْ عَذَابُ يَوْمِ الظُّلَّةِ إِنَّهُ كَانَ عَذَابَ يَوْمٍ عَظِيمٍ

So they impugned him, and then they were overtaken by the punishment of the day of the overshadowing cloud. It was indeed the punishment of a terrible day.