وَإِذْ تَأَذَّنَ رَبُّكَ لَيَبْعَثَنَّ عَلَيْهِمْ إِلَىٰ يَوْمِ ٱلْقِيَـٰمَةِ مَن يَسُومُهُمْ سُوٓءَ ٱلْعَذَابِ ۗ إِنَّ رَبَّكَ لَسَرِيعُ ٱلْعِقَابِ ۖ وَإِنَّهُۥ لَغَفُورٌ رَّحِيمٌ
And when your Lord proclaimed that He would surely send against them, until the Day of Resurrection, those who would inflict on them a terrible punishment. Indeed your Lord is swift in retribution, and indeed, He is all-forgiving, all-merciful.