They disbelieved him and, consequently, they incurred the retribution of the Day of the Canopy. It was the retribution of an awesome day.
فَكَذَّبوهُ فَأَخَذَهُم عَذابُ يَومِ الظُّلَّةِ إِنَّهُ كانَ عَذابَ يَومٍ عَظيمٍ
fakazzaboohu fa akhazahum ‘azaabu Yawmiz zullah; innahoo kaana ‘azaaba Yawmin ‘Azeem