﴿ هَلْ يَنظُرُونَ إِلَّا ٱلسَّاعَةَ أَن تَأْتِيَهُم بَغْتَةًۭ وَهُمْ لَا يَشْعُرُونَ ﴾

“ARE THEY [who are lost in sin] but waiting for the Last Hour - [waiting] that it come upon them of a sudden, without their being aware [of its approach]?”

Please check ayah 43:73 for complete tafsir.