Surah As-Saffat — Ayah 19 (37:19)
فَإِنَّمَا هِيَ زَجۡرَةٞ وَٰحِدَةٞ فَإِذَا هُمۡ يَنظُرُونَ ١٩
English translation (Saheeh International)
It will be only one shout, and at once they will be observing.
Brief commentary
It will only be one blow of the trumpet (the second blowing), and suddenly they will all be looking at the horrors of the Day of Judgement, awaiting what Allah will do with them.