Tafseer Ibn Kathir of ASY SYU'ARAA' [189]

فَكَذَّبُوهُ فَأَخَذَهُمْ عَذَابُ يَوْمِ الظُّلَّةِ إِنَّهُ كَانَ عَذَابَ يَوْمٍ عَظِيمٍ

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.