﴿ وَيَسْتَعْجِلُونَكَ بِٱلْعَذَابِ ۚ وَلَوْلَآ أَجَلٌۭ مُّسَمًّۭى لَّجَآءَهُمُ ٱلْعَذَابُ وَلَيَأْتِيَنَّهُم بَغْتَةًۭ وَهُمْ لَا يَشْعُرُونَ ﴾

“Now they challenge thee to hasten the coming upon them of [God’s] chastisement: and indeed, had not a term been set [for it by God], that suffering would already have come upon them! But indeed, it will most certainly come upon them of a sudden, and they will be taken unawares.”

Please check ayah 29:55 for complete tafsir.