إِنَّمَا الْمُؤْمِنُونَ إِخْوَةٌ فَأَصْلِحُوا بَيْنَ أَخَوَيْكُمْ وَاتَّقُوا اللَّهَ لَعَلَّكُمْ تُرْحَمُونَ ﴿۱۰﴾ يَا أَيُّهَا الَّذِينَ آمَنُوا لَا يَسْخَرْ قَوْمٌ مِنْ قَوْمٍ عَسَى أَنْ يَكُونُوا خَيْرًا مِنْهُمْ وَلَا نِسَاءٌ مِنْ نِسَاءٍ عَسَى أَنْ يَكُنَّ خَيْرًا مِنْهُنَّ وَلَا تَلْمِزُوا أَنْفُسَكُمْ وَلَا تَنَابَزُوا بِالْأَلْقَابِ بِئْسَ الِاسْمُ الْفُسُوقُ بَعْدَ الْإِيمَانِ وَمَنْ لَمْ يَتُبْ فَأُولَئِكَ هُمُ الظَّالِمُونَ ﴿۱۱﴾

﴾10﴿ Innamal mu'minoona ikhwatun fa aslihoo baina akhawaykum wattaqul laaha la'allakum turhamoon
﴾11﴿ Yaaa ayyuhal lazeena aamanoo laa yaskhar qawmum min qawmin 'asaaa anyyakoonoo khairam minhum wa laa nisaaa'um min nisaaa'in 'Asaaa ay yakunna khairam minhunna wa laa talmizooo anfusakum wa laa tanaabazoo bil alqaab; bi'sal ismul fusooqu ba'dal eemaan; wa mal-lam yatub fa-ulaaa'ika humuz zaalimoon

﴾10﴿ Indeed, the believers are but brothers. So reconcile between your brothers and fear Allah the Exalted so that you may be shown mercy
﴾11﴿ O believers, let not some men ridicule others, for it may be that they are better than them. And let not some women ridicule others, for it may be that they are better than them. And do not insult one another, nor call each other by offensive nicknames. Evil is the name of wickedness after having faith. And whoever does not repent—then those are the wrongdoers

[10] This is the reason for the command to make reconciliation.
In the word (الْمُؤْمِنُونَ), there is an indication that lineage and ancestry hold no real value; rather, it is solely faith that serves as the basis for brotherhood and unity.
[11] This is the fifth point of etiquette: when fighting between two groups ends, the faults and shortcomings of each side may have become exposed.
However, after reconciliation, it is not permissible to belittle or insult one another because of those past faults, lest discord and conflict arise again.
In this etiquette, three things are prohibited, as they lead to insulting Muslims and can cause further corruption.
The first is mockery – that is, looking down upon someone because of a flaw, or even without a flaw, treating them with contempt and indirectly hinting at their defects, even without stating them openly.
Mockery involves arrogance, which is a trait of disbelievers and polytheists who mock the people of truth.
(قَوْمٌ مِنْ قَوْمٍ) – The term “qawm” is used because when one person from a group is called upon in difficulty, the others support him.
These traits are usually found in men, so the term “qawm” is originally used for men, and women are included in it only metaphorically at times.
(وَلَا نِسَاءٌ) – Women are mentioned separately here for two reasons: first, because mockery among women is more frequent, and second, because usually men do not mock women, nor women men; rather, each gender tends to mock their own kind.
(عَسَى أَنْ يَكُونُوا خَيْرًا مِنْهُمْ) – This has two meanings:
1. The person being mocked may appear insignificant outwardly, but in truth, may be close and beloved to Allah the Exalted.
2. It may happen that in the future, the mocking person becomes humiliated and disgraced, while the one mocked becomes honored—thus, the roles will be reversed.
The second thing that is prohibited, and which leads to family and social discord, is mentioned in the phrase:
(وَلَا تَلْمِزُوا أَنْفُسَكُمْ) – “Do not insult one another.”
Lamez refers to criticizing or insulting someone to their face, and originally included gestures with the eyes, head, or lips, along with hidden words.
Hamz, by contrast, is about finding faults in someone's absence.
Thus, lamez is worse than hamz, and the latter is addressed in the next verse in the context of backbiting.
When you insult someone to their face, it is a direct humiliation of a Muslim.
The third prohibited thing that causes discord and humiliation among Muslims is found in the phrase:
(وَلَا تَنَابَزُوا بِالْأَلْقَابِ) – “Do not call each other with offensive nicknames.”
This also implies arrogance in the one using the nickname and contempt for the other Muslim.
Nabz refers to mentioning a title or nickname, and is mostly used for offensive ones.
A nickname is any descriptive term, besides a person's actual name, that is used either to elevate or humiliate them.
So the meaning of this phrase is: do not call a Muslim by a nickname that hurts them and is intended to belittle them—like calling someone “O fasiq,” “O hypocrite,” “O disbeliever,” “O Jew,” “O Christian,” “O donkey,” or “O pig.”
(بِئْسَ الِاسْمُ الْفُسُوقُ بَعْدَ الْإِيمَانِ) – One meaning is: these names which indicate sinful behavior (like fasiq, hypocrite, Jew, Christian) are terrible when used for a believer after he has embraced faith.
Another meaning is: using such names for a believer leads to fisq (sinful behavior), thus making the speaker himself sinful.
In a sound hadith, it is narrated that when someone says to his brother, “O disbeliever,” one of the two becomes guilty of it:
If the person truly is a disbeliever, then the statement is true; but if not, then the sin of the word returns to the one who said it.