His words, Exalted is He:

The Crashing Blow! What is the Crashing Blow?

He said:

God strikes His enemies a crashing blow through His punishment.

What will show you what the Crashing Blow is?

This is a way of magnifying it due to its severity (shidda). Everything in the Qurʾān which is preceded by the words: What will show you? is something about which He has not yet provided information, just as He said: And what will explain [it] to you? The Hour may well be near [33:63]; He had not informed [the Prophet] of it up until His words: What will show you what the Crashing Blow is? Then He informed [him] about it.

His words, Exalted is He:

A day [when] people will be like scattered moths.

This means that they will bump into each other because of the awe (hayba) [they experience] before God, Mighty and Majestic is He. It has been said: the blow (qaraʿ) is threefold: the blow which strikes bodies is the arrow of death; the blow which strikes works is God’s questioning them; and the blow which strikes hearts is the fear of alienation.

But God, Glorified and Exalted is He, knows best.