Previous ayaat carried the condemnation of those who refused to believe in Allah subhanahu wa ta’ala and in the Akhirah and were miserly. The present ayaat persuade people to believe in Allah subhanahu wa ta’ala and the akhirah and engage in the gainful activity of spending in the way of Allah. Then, towards the end [41-42], a description of the trying situations prevailing on the plains of Resurrection appears to warn people, who refuse to believe and refuse to do what is good, of their evil end.
The text says:
that is, Allah subhanahu wa ta’ala does not allow the reward of good deeds from anyone be reduced in any manner or quantity whatsoever. In fact, He adds extra rewards, in multiples, in special Divine favors, and the life of akhirah will witness this supreme mercy of the Lord.
With Allah, the least human measure of thawab or reward is that one good deed gets recorded as ten. Then, this does not stop at that; through sheer mercy and grace, Allah subhanahu wa ta’ala bestows manifold increase into this treasure of good deeds. Some hadith narrations tell us that there are deeds the reward for which rises as high as two million times. The truth of the matter is that Allah is al-Kareem, the most Noble, the most Generous – He Himself, in His limitless mercy and grace, so increases the quantum of his blessing on His servants that it simply cannot be counted or measured in our human terms. The extent of His generosity and the dimensions of His very Being are beyond human conceptualization – who can dare calculate the uncalculable?
Incidentally, the word ذَرَّةٍ dharrah appearing in this ayah has been translated here as ‘particle’ following the generally recognized meaning it carries. However, some commentators have pointed out that ‘dharrah’ is the name of the smallest kind of red ant which the people of Arabia used to cite as an example of something very light and insignificantly small.
In the ayah  beginning with: فَكَيْفَ إِذَا جِئْنَا مِن كُلِّ أمَّةٍ , there is an invitation to visualize, in range and depth, the gravity of what will happen on the site of the Last Day. Also intended is an admonition to the disbelievers from the tribe of Quraysh. Their anxiety would know no bounds when every prophet of every community would appear as a witness to the good or bad deeds of his respective community on the Last Day – and Muhammad sallAllahu aalyhi wa sallam too, the last of the prophets, will appear as a witness over his community – and he would give witness in the Divine Court particularly about such disbelievers and polytheists declaring that these people saw open signs and miracles, yet they belied and rejected them and ultimately refused to believe in “The Divinity and my Prophethood”.
According to a narration in Bukhari, Rasoolullah sallAllahu aalyhi wa sallam asked Abdullah ibn Masud radhiAllahu anhu to recite the Qur’an to him. Abdullah said: “You want to hear it from me, although the Qur’an was revealed to you?” He said: “Yes. Recite.” Abdullah ibn Masud says: “I started reciting Suratun-Nisa and when I reached the ayah: فَكَيْفَ إِذَا جِئْنَا مِن كُلِّ أمَّةٍ بِشَهِيدٍ 41, he said: “Enough for now;” and when I raised my eyes to look at him, I saw tears trickling from his blessed eyes.”
Allama al-Qastalani writes: This ayah caused a full view of the akhirah to be present before his eyes and he thought about the people of his community who were short on or lacking in good deeds and that was why tears started flowing from his eyes.
Some commentators have said that the word, هَـؤُلاءِ them, in this ayah [4:41] points to the disbelievers and hypocrites present during the age of prophethood. Some others say that it refers to the entire community right through the Day of Resurrection. This is so because, as indicated in some hadeeth narrations, the deeds of his community are being continuously presented before him. Nevertheless, from here we know that the prophets of past communities and that the Prophet sallAllahu aalyhi wa sallam too will testify to the deeds of his community. This textual style of the Qur’an tells us that there is to be no prophet after him who could appear as a witness over a possible community of his – otherwise, the Qur’an would have mentioned him and his community and the testimony he would give. Seen from this angle, this ayah is a proof of the finality of prophethood as well.
In يَوْمَئِذٍ يَوَدُّ الَّذِينَ كَفَرُواْ the text mentions the state of utter despair faced by disbelievers on the Last Day. That day they would wish to go extinct rather than face its ordeal, to become a patch of the earth underneath, or wish that the earth would crack open, suck them in leaving nothing on top but dust mingled with dust, so that they would be delivered of the scrutiny and retribution of that fateful time.
The statement: لَوْ تُسَوَّى بِهِمُ الاٌّرْضُ 4:42 has been translated here literally to express, in some measure at least, the power and poignancy of the original Qur’anic expression, as: ‘shall wish that the earth be leveled with them’.
On the plains of Resurrection the disbelievers will see that all animals have been turned into dust after having exchanged the retribution of each other’s excesses. They too, would pine for an end like this wishing to have become all dust.
Finally, the ayah says
It means that these disbelievers will be unable to keep anything about their beliefs and deeds concealed from Allah. their own hands and feet will confess. The Prophets will testify and, of course, present there will be everything on record in their Book of Deeds.
Ibn Abbas radhiAllahu anhu was asked: “At one place, the Qur’an says: ‘And they shall not conceal anything from Allah’ [4:42]; while at another place, it says: ‘By Allah, our Lord, we were no mushriks’ [6:23] – Is there, as it seems, any contradiction between the two ayaat?” To this he replied:
‘What will happen is that when the disbelievers will begin to see that nobody except true Muslims are being admitted into the Paradise they would decide to refuse point-blank that they had ever committed shirk or any other evil deed, in the hope that the plan works and results in their salvation. But, soon after this refusal of theirs, the very parts of their body would testify against them, which would totally frustrate their plan to conceal the truth about their deeds. That will be the time when they will confess everything. Hence: “They shall not conceal anything from Allah”.