Allah gives Respite to the Disbelievers and is never unaware of what They do
Allah says, `O Muhammad, do not think that Allah is unaware of what the unjust disbelievers do. Do not think because Allah gave them respite and delayed their punishment that He is unaware or ignoring punishing them for what they do. Rather, Allah keeps full account of this for them and keeps it on record against them,
إِنَّمَا يُؤَخِّرُهُمْ لِيَوْمٍ تَشْخَصُ فِيهِ الأَبْصَـرُ
(but He gives them respite up to a Day when the eyes will stare in horror.) from the horror of the Day of Resurrection.' Allah next mentions how they will all be raised up from their graves and hurriedly gathered for the Day of Gathering,
Continue reading the tafsir of ayahs 42–43 In the second verse (43), it has been said that the postponement of sudden punishment against these unjust people is not any better for them because, ultimately, they will be seized in the great punishment of the Qiyamah and the 'Akhirah which will overtake them all of a sudden. The details of this punishment in the life to come and the horrendous happenings to be experienced there keep appearing right upto the end of the verse:
لِيَوْمٍ تَشْخَصُ فِيهِ الْأَبْصَارُ
A day when the eyes shall remain upraised (in terror).
مُهْطِعِينَ مُقْنِعِي رُءُوسِهِمْ
They shall be rushing with their heads raised upward.
لَا يَرْتَدُّ إِلَيْهِمْ طَرْفُهُمْ
Their eyes shall not return towards them.
وَأَفْئِدَتُهُمْ هَوَاءٌ ,
And their hearts shall be hollow.
After the shape of things to come upon them has been stated, the address is to the Holy Prophet ﷺ who has been asked to warn his people of the punishment of that day, the day on which the unjust and the wrong-doing will have no choice but to call their Lord for some more time to return to the world they knew so that they could say yes to the call of prophets and follow them this time and may thereby have their deliverance from this punishment. The answer to their request will come from Allah Ta’ ala wherein it will be said: This is what you are saying now. Is it not that you had been giving sworn statements to the effect that your wealth and power shall never part with you, and that you shall go on living in the world just like that, in comfort and luxury, forever; and is it not that you had rejected the idea that you will live again and that there was a world hereafter?
When the Truth presents itself to a man, he sets himself against it. He shows such fearlessness in the face of it, as if there were nobody else in the world more courageous than he. But this very Truth which is made manifest by a preacher of God’s word in the present world, will become evident in the Hereafter at the level of God; the opponents of Truth will then lose all their bravado. After seeing the horrible scenes of the Hereafter, their condition will be such that their eyes will leap from their heads; they will not even be able to wink. Tilting their heads back, they will rush towards the ground where all will be gathered and their hearts will be terror-struck.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.