وَإِذ تَأَذَّنَ رَبُّكَ لَيَبعَثَنَّ عَلَيهِم إِلىٰ يَومِ القِيامَةِ مَن يَسومُهُم سوءَ العَذابِ ۗ إِنَّ رَبَّكَ لَسَريعُ العِقابِ ۖ وَإِنَّهُ لَغَفورٌ رَحيمٌ

And [mention] when your Lord declared that He would surely [continue to] send upon them until the Day of Resurrection those who would afflict them with the worst torment. Indeed, your Lord is swift in penalty; but indeed, He is Forgiving and Merciful.