وَنَضَعُ الْمَوَازِينَ الْقِسْطَ لِيَوْمِ الْقِيَامَةِ فَلَ تُظْلَمُ نَفْسٌ شَيْيًا
And We shall set up Balances of justice on the Day of Resurrection, then none will be dealt with unjustly in anything.
meaning, "We shall set up the Balances of justice on the Day of Resurrection."
The majority of scholars state that it is one Balance, and the plural form is used here to reflect the large number of deeds which will be weighed therein.
فَلَ تُظْلَمُ نَفْسٌ شَيْيًا
وَإِن كَانَ مِثْقَالَ حَبَّةٍ مِّنْ خَرْدَلٍ أَتَيْنَا بِهَا وَكَفَى بِنَا حَاسِبِينَ
then none will be dealt with unjustly in anything. And if there be the weight of a mustard seed, We will bring it. And sufficient are We to take account.
This is like the Ayat;
وَلَا يَظْلِمُ رَبُّكَ أَحَدًا
and your Lord treats no one with injustice. (18;49)
إِنَّ اللَّهَ لَا يَظْلِمُ مِثْقَالَ ذَرَّةٍ وَإِن تَكُ حَسَنَةً يُضَـعِفْهَا وَيُوْتِ مِن لَّدُنْهُ أَجْراً عَظِيماً
Surely, Allah wrongs not even of the weight of speck of dust, but if there is any good, He doubles it, and gives from Him a great reward. (4;40)
يبُنَىَّ إِنَّهَأ إِن تَكُ مِثْقَالَ حَبَّةٍ مِّنْ خَرْدَلٍ فَتَكُنْ فِى صَخْرَةٍ أَوْ فِى السَّمَـوَتِ أَوْ فِى الاٌّرْضِ يَأْتِ بِهَا اللَّهُ إِنَّ اللَّهَ لَطِيفٌ خَبِيرٌ
"O my son! If it be equal to the weight of a grain of mustard seed, and though it be in a rock, or in the heavens or in the earth, Allah will bring it forth. Verily, Allah is Subtle, Well-Aware." (31;16)
In the Two Sahihs it was recorded that Abu Hurayrah said that the Messenger of Allah said;
كَلِمَتَانِ خَفِيفَتَانِ عَلَى اللِّسَانِ ثَقِيلَتَانِ فِي الْمِيزَانِ حَبِيبَتَانِ إِلَى الرَّحْمَنِ
سُبْحَانَ اللهِ وَبِحَمْدِهِ سُبْحَانَ اللهِ الْعَظِيم
Two words which are light on the tongue, heavy in the Balance and beloved to Ar-Rahman;
"Subhan Allahi wa bi hamdihi, Subhan Allahil `Azim (Glory and praise be to Allah, Glory be to Allah the Almighty)."
Imam Ahmad also recorded that A'ishah said that;
one of the Companions of the Messenger of Allah sat down before him and said, "O Messenger of Allah, I have two slaves who lie to me, betray me and disobey me, and I hit them and insult them. How do I stand with regard to them?"
The Messenger of Allah said;
يُحْسَبُ مَا خَانُوكَ وَعَصَوْكَ وَكَذَّبُوكَ وَعِقَابُكَ إِيَّاهُمْ فَإِنْ كَانَ عِقَابُكَ إِيَّاهُمْ بِقَدْرِ ذُنُوبِهِمْ كَانَ كَفَافًا لَا لَكَ وَلَا عَلَيْكَ وَإِنْ كَانَ عِقَابُكَ إِيَّاهُمْ دُونَ ذُنُوبِهِمْ كَانَ فَضْلً لَكَ وَإِنْ كَانَ عِقَابُكَ إِيَّاهُمْ فَوْقَ ذُنُوبِهِمْ اقْتُصَّ لَهُمْ مِنْكَ الْفَضْلُ الَّذِي بَقِيَ قَبْلَك
The extent to which they betrayed you, disobeyed you and lied to you will be measured against the punishment you meted out to them. If your punishment was commensurate with their misconduct, then you will be equal and you will not have anything counted for you or against you.
If your punishment of them was less than that what they deserved for their misconduct, then this will count in your favor. If your punishment of them was more than what they deserved for their misconduct, then Allah will take what is due to them from you.
Then the man started to weep before the Messenger of Allah, and the Messenger of Allah asked,
مَالَهُ لَاا يَقْرَأُ كِتَابَ الله
وَنَضَعُ الْمَوَازِينَ الْقِسْطَ لِيَوْمِ الْقِيَامَةِ فَلَ تُظْلَمُ نَفْسٌ شَيْيًا وَإِن كَانَ مِثْقَالَ حَبَّةٍ مِّنْ خَرْدَلٍ أَتَيْنَا بِهَا وَكَفَى بِنَا حَاسِبِينَ
What is the matter with him Has he not read the words of Allah,
And We shall set up Balances of justice on the Day of Resurrection, then none will be dealt with unjustly in anything. And if there be the weight of a mustard seed, We will bring it. And sufficient are We to take account.
The man said, "O Messenger of Allah, I think there is nothing better than keeping away from these people -- meaning his slaves -- I call upon you to bear witness that they are all free.