Taha 20:129

Walawla kalimatun sabaqat minrabbika lakana lizaman waajalun musamma

And if not for a word that preceded from your Lord, it [i.e., punishment] would have been an obligation [due immediately], and [if not for] a specified term [decreed].

But for a word from your Lord that had passed earlier, and an appointed time that had been fixed, it (the punishment) would have been inevitable (for them).