Turning away.

That is:

When it is said to them, 'Fear what is before you'

and what is behind you, they turn away.

The precise investigation regarding the word 'Idh':

And let it be known also that the origin in such statements of His

- He is Exalted - 'And when your Lord said to the angels'

and 'And when Moses said'

is that the word 'idh' is a verbal adverb,

but it has been shifted to signify frightening, terrifying, and the like.

It is as if a person is bringing to mind terrifying places

or immense, terrifying events without structuring sentences,

and without the words falling into any realm of grammatical inflection,

for the desired purpose is to bring them to mind and mention them

until their prominent image is etched in the addressee's mind,

and fear of them and their terrifying nature take over his heart and conscience.

Thus, the accurate verification is that in such places

there is no need to search and inquire about the governing agents for this word,

and Allah knows best.

Omission of the preposition:

And let it be known also that omitting the preposition from the infinitive 'an' is consistent in Arab speech,

and the intended meaning then is 'li-an' (so that) or 'bi-an' (by that).

Omission of the conditional response:

And let it be known also that the origin in such statements of His

- He is Exalted - 'And if you could see when the wrongdoers are in the overwhelming depths of death'

and 'And if those who did wrong would see when they see the punishment'.