Ayah

وَلَوۡلَا كَلِمَةٌ سَبَقَتۡ مِن رَّبِّكَ لَكَانَ لِزَامًا وَأَجَلٌ مُّسَمًّى
Translation

Had it not been for a Word that went forth before from thy Lord, (their punishment) must necessarily have come; but there is a Term appointed (for respite).<br/>
Tafsir

And but for a decree that had already preceded from your Lord, that their chastisement be deferred to the Hereafter, it, destruction, would have been an inevitability, [their destruction] would have been necessary in this world, and a specified term, fixed for them (ajalun musamman, a supplement to the pronoun concealed in kaana, 'it would have been', the separation [of both subjects] by the predicate of both serves as an emphasis).