That I might do righteousness in that which I left behind." No! It is only a word he is saying; and behind them is a barrier until the Day they are resurrected.
The Disbelievers' Hope when death approaches Allah tells us about what happens when death approaches one of the disbelievers orone of those who have been negligent with the commands of Allah. He tells us what he says and how he asks to come back to this world so that he can rectify whatever wrongs he committed during his lifetime. Allah says:
Never! It is just a word he has to utter. And in front of them there is a barrier till the day when they will be resurrected. (23:100)
The word بَرْزَخٌ (Barzakh) means "barrier" and implies anything which intervenes between two conditions or two objects. For this reason it also means the intervening period between death and the Day of Judgment. The meaning of this verse is that the wish of the infidel who has died to be returned to this world is fruitless, because he has reached the Barzakh from which no return is possible and a second life cannot be given until the Day of Resurrection, when all the dead will rise and be brought back to life.
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 98–103
When God’s preacher calls for the Truth, it often happens that those whom he addresses, instead of acknowledging it, become his enemies. They make him the target of mischief and spread false propaganda against him. At that time, he has the urge to react. He feels that if he has been maltreated by others, he should also retaliate. He feels that if he keeps quiet, will be encouraged and they will be emboldened to engage in further opposition. But all such thoughts are instigations of Satan. At this critical juncture, Satan confuses the issue with a view to leading man astray. On such occasions, one who is a believer should seek God’s protection, will cast him into manifest error.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.