We know that Allah (swt) is the absolute justice, and does not oppress people.

 وَمَا رَبُّكَ بِظَلَّامٍ لِّلْعَبِيدِ

(And your Lord is not ever unjust to [His] servants.) (Fussilat: 46)

A person either wrongs himself by offering immediate pleasure to permanent bliss, or wrongs others. The Prophet (saws) said among what he narrated from Allah (swt that He has said:

“O MY slaves, I have made oppression unlawful for myself and I have made it unlawful among you, so do not oppress one another.”

We know that the supplication of the one who has been wronged and who has just ended his fast have unrejected supplication, and as the Prophet (saws) said:

“..raised by God above the clouds and for which the gates of heaven are opened. The Lord says, ‘I swear by my might that I will certainly help you, though it be after some time.”[1]

But Allah (swt) never wrongs anyone.

(… إِنَّ اللَّهَ لَا يَظْلِمُ مِثْقَالَ ذَرَّةٍ ۖ ) (Indeed, Allah does not do injustice, [even] as much as an atom’s weight; …): Some ignorant people who do not contemplate the Holy Quran said: The atom is not the smallest element in the universe. Years ago, the atom was smashed into neutrons and electrons, which are smaller than the atom, and Allah (swt) says:

 فَمَن يَعْمَلْ مِثْقَالَ ذَرَّةٍ خَيْرًا يَرَهُ % وَمَن يَعْمَلْ مِثْقَالَ ذَرَّةٍ شَرًّا يَرَهُ

(So whoever does an atom’s weight of good will see it, % And whoever does an atom’s weight of evil will see it.) (Az-Zalzala: 7-8)

Yes indeed, the atom was smashed into smaller elements, but they did not read this verse which refers to smaller parts of atom:

 وَمَا يَعْزُبُ عَن رَّبِّكَ مِن مِّثْقَالِ ذَرَّةٍ فِي الْأَرْضِ وَلَا فِي السَّمَاءِ وَلَا أَصْغَرَ مِن ذَٰلِكَ وَلَا أَكْبَرَ

(And not absent from your Lord is any [part] of an atom’s weight within the earth or within the heaven or [anything] smaller than that or greater) (Yunus: 61)

Additionally, when Allah (swt) talks about justice, says:

 وَنَضَعُ الْمَوَازِينَ الْقِسْطَ لِيَوْمِ الْقِيَامَةِ فَلَا تُظْلَمُ نَفْسٌ شَيْئًا ۖ وَإِن كَانَ مِثْقَالَ حَبَّةٍ مِّنْ خَرْدَلٍ أَتَيْنَا بِهَا ۗ وَكَفَىٰ بِنَا حَاسِبِينَ

(And We place the scales of justice for the Day of Resurrection, so no soul will be treated unjustly at all. And if there is [even] the weight of a mustard seed, We will bring it forth. And sufficient are We as accountant.) (Al-Anbiyaa: 47)

Allah (swt) as well holds account the humans for every minute matters:

 يَا بُنَيَّ إِنَّهَا إِن تَكُ مِثْقَالَ حَبَّةٍ مِّنْ خَرْدَلٍ فَتَكُن فِي صَخْرَةٍ أَوْ فِي السَّمَاوَاتِ أَوْ فِي الْأَرْضِ يَأْتِ بِهَا اللَّهُ ۚ إِنَّ اللَّهَ لَطِيفٌ خَبِيرٌ

(O my son, indeed if wrong should be the weight of a mustard seed and should be within a rock or [anywhere] in the heavens or in the earth, Allah will bring it forth. Indeed, Allah is Subtle and Acquainted) (Lugman: 16)

(… وَإِن تَكُ حَسَنَةً يُضَاعِفْهَا …) (…while if there is a good deed, He multiplies it …): Multiplies it not just once rather seven hundreds times and even more as He (swt) says:

 مَّثَلُ الَّذِينَ يُنفِقُونَ أَمْوَالَهُمْ فِي سَبِيلِ اللَّهِ كَمَثَلِ حَبَّةٍ أَنبَتَتْ سَبْعَ سَنَابِلَ فِي كُلِّ سُنبُلَةٍ مِّائَةُ حَبَّةٍ ۗ وَاللَّهُ يُضَاعِفُ لِمَن يَشَاءُ ۗ وَاللَّهُ وَاسِعٌ عَلِيمٌ

(The example of those who spend their wealth in the way of Allah is like a seed [of grain] which grows seven spikes; in each spike is a hundred grains. And Allah multiplies [His reward] for whom He wills. And Allah is all-Encompassing and Knowing) (Al-Baqara: 261)

( وَيُؤْتِ مِن لَّدُنْهُ أَجْرًا عَظِيمًا … ) (…and gives from Himself a great reward): One year, the rains did not come and there was a drought in Madina, during the rule of Omar Ibn Al-Khattab, a caravan laden down with food came, people of Madina were out of food due to the drought, so the merchants wanted to buy the food from this caravan so they could sell it with high prices to people. However, Uthman Ibn Affan (May Allah be pleased with him) bought the whole caravan, then the merchants went to him saying: “O’ Uthman, we are ready to pay you multiple price of what you have paid. He said: “I have already received a better offer.” They raised their offers, again and again, but each time Uthman declined, repeating, “I have already received a better offer.” Finally, the merchants made their best offer: five times the value of the cargo, but Uthman said: I have received a better offer from Allah, for Allah has said that anyone who gives away wealth in Allah’s name will get back far more than he gave away.”

Islam taught us how to fight monopoly, Uthman (may Allah be pleased with him) monopolized in favor of the poor, so he bought the whole caravan to prevent monopoly and give charity to the poor, here Allah (swt) multiplies the good deed:

 مَّن ذَا الَّذِي يُقْرِضُ اللَّهَ قَرْضًا حَسَنًا فَيُضَاعِفَهُ لَهُ أَضْعَافًا كَثِيرَةً ۚ وَاللَّهُ يَقْبِضُ وَيَبْسُطُ وَإِلَيْهِ تُرْجَعُونَ

(Who is it that would loan Allah a goodly loan so He may multiply it for him many times over? And it is Allah who withholds and grants abundance, and to Him you will be returned.) (Al-Baqara: 245)

Do not ask how much this grant because Allah’s bounties are not as ours the humans.

[1] Sahih Muslim, Book of Righteousness, Relationship and Ethics, Chapter of Prohibiting the injustice, Hadith No. 2577.