Allah said,

And Our commandment is but one as the twinkling of an eye.

This is information about the execution of His will in His creation, just as He informed us the execution of His decree in them,

And Our commandment is but one

meaning, We only command a thing once, without needing to repeat the command; and whatever We command comes to existence faster than the blinking of an eye without any delay, not even for an instant.' Allah said,

And indeed, We have destroyed your likes, i.e. the earlier nations who denied their Messengers,

then is there any that will remember? meaning, is there any that will receive admonition by remembering the humiliation and torment that Allah decreed for them?

And a barrier will be set between them and that which they desire, as was done in the past with the people of their kind.

Allah's statement,

And everything they have done is noted in Az-Zubur.

meaning, everything they did is recorded in the Books of Record entrusted to the angels, peace be upon them,

And everything, small and large, meaning, of their actions,

is written down. everything that they do is recorded and written in their Record of deeds, which leave nothing, whether large or small, but it is recorded and counted.

Imam Ahmad recorded that 'A'ishah said that the Messenger of Allah said,

"O 'A'ishah! Beware of small sins, because there is someone assigned by Allah who records them."

An-Nasa'i and Ibn Majah also collected this Hadith.