( وَإِذْ تَأَذَّنَ رَبُّكَ ) (And [mention] when your Lord declared): The linguistic root of the Arabic word used for the verb (to declare) means (to inform), and it is also used to call to prayer (athan); an announcement of entry of the designated time. This expression indicates that there is no doubt whatsoever that the statement given by Allah (swt) will be fulfilled.

( لَيَبْعَثَنَّ عَلَيْهِمْ إِلَىٰ يَوْمِ الْقِيَامَةِ ) (that He would surely [continue to] send upon them until the Day of Resurrection): It will be sent upon the people of Children of Israel who went astray.

( مَن يَسُومُهُمْ سُوءَ الْعَذَابِ) (those who would afflict them with the worst torment): Allah (swt) would send against them those who would inflict cruel suffering upon them.

( إِنَّ رَبَّكَ لَسَرِيعُ الْعِقَابِ ) (Indeed, your Lord is swift in penalty): Human beings believe that punishment is postponed, but the truth is that punishment is swift. Similarly, the period of time that people spend on this earth, no matter how long it may be, will seem in the Afterlife as mere minutes:

  كَأَنَّهُمْ يَوْمَ يَرَوْنَهَا لَمْ يَلْبَثُوا إِلَّا عَشِيَّةً أَوْ ضُحَاهَا

(It will be, on the Day they see it, as though they had not remained [in the world] except for an afternoon or a morning thereof.) (An-Naazi’aat: 46)

( وَإِنَّهُ لَغَفُورٌ رَّحِيمٌ ) (Indeed, your Lord is swift in penalty): Allah (swt) punishes for the wrongdoings and transgressions committed by human beings, yet He (swt) is also the Forgiving and Merciful; forgiving sins and deleting them, and bestowing abundant goodness from His (swt) Mercy and Generosity.