﴿ وَإِذْ تَأَذَّنَ رَبُّكَ لَيَبْعَثَنَّ عَلَيْهِمْ إِلَىٰ يَوْمِ ٱلْقِيَٰمَةِ مَن يَسُومُهُمْ سُوٓءَ ٱلْعَذَابِ ۗ إِنَّ رَبَّكَ لَسَرِيعُ ٱلْعِقَابِ ۖ وَإِنَّهُۥ لَغَفُورٌۭ رَّحِيمٌۭ ﴾

“And lo! Thy Sustainer made it known that most certainly He would rouse against them, unto Resurrection Day, people who would afflict them with cruel suffering: verily, thy Sustainer is swift in retribution - yet, verily, He is [also] much-forgiving, a dispenser of grace.”

(And (remember) when thy Lord proclaimed that He would raise against them till the Day of Resurrection those who would lay on them a cruel torment) those who would severely torment them by the imposition of the capitation tax and other things, the reference here is to Muhammad (pbuh) and his Community. (Lo! verily your Lord is swift in prosecution) He has a severe punishment for those who do not believe in Him (and lo! verily He is Forgiving, Merciful) vis-�-vis those who believe in Him.