وَإِذْ تَأَذَّنَ رَبُّكَ لَيَبْعَثَنَّ عَلَيْهِمْ إِلَىٰ يَوْمِ ٱلْقِيَـٰمَةِ مَن يَسُومُهُمْ سُوٓءَ ٱلْعَذَابِ ۗ إِنَّ رَبَّكَ لَسَرِيعُ ٱلْعِقَابِ ۖ وَإِنَّهُۥ لَغَفُورٌ رَّحِيمٌ
Wai th taa thth ana rabbuka layabAAathanna AAalayhim il a yawmi alqiy a mati man yasoomuhum sooa alAAa tha bi inna rabbaka lasareeAAu alAAiq a bi wainnahu laghafoorun ra h eem un 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.
 - Mohammad Asad
Also remind them when your Rabb declared that He would raise against them others who would afflict them with severe torment till the Day of Resurrection. Swift is the retribution of your Rabb, yet He is also the Forgiving, Merciful.
 - Muhammad Farooq-i-Azam Malik
And 'remember, O Prophet,' when your Lord declared that He would send against them others who would make them suffer terribly until the Day of Judgment. Indeed, your Lord is swift in punishment, but He is certainly All-Forgiving, Most Merciful.
 - Mustafa Khattab
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. Lo! verily thy Lord is swift in prosecution and lo! verify He is Forgiving, Merciful.
 - Marmaduke Pickthall
Behold! thy Lord did declare that He would send against them to the Day of Judgment those who would afflict them with grievous penalty. Thy Lord is quick in retribution but he is also Oft-Forgiving Most Merciful. 1140
 - Abdullah Yusuf Ali