And they denied him, so the punishment of the day of the black cloud seized them. Indeed, it was the punishment of a terrible day.
The Saheeh International Quran Translation
فَكَذَّبُوهُ فَأَخَذَهُمْ عَذَابُ يَوْمِ ٱلظُّلَّةِ إِنَّهُۥ كَانَ عَذَابَ يَوْمٍ عَظِيمٍAnd they denied him, so the punishment of the day of the black cloud seized them. Indeed, it was the punishment of a terrible day.