Al-Mundhiri recorded the following chapter in his book Al-Targhib wal-Tarhib:

الترهيب من احتقار المسلم وأنه لا فضل لأحد على أحد إلا بالتقوى

Discouragement of belittling Muslims and that no one is favored over another except by righteousness.

Source: al-Targhīb wal-Tarhīb 3/609

Abu Huraira reported: The Messenger of Allah, peace and blessings be upon him, said:

بِحَسْبِ امْرِئٍ مِنْ الشَّرِّ أَنْ يَحْقِرَ أَخَاهُ الْمُسْلِمَ كُلُّ الْمُسْلِمِ عَلَى الْمُسْلِمِ حَرَامٌ دَمُهُ وَمَالُهُ وَعِرْضُهُ

It is enough evil for a man to look down upon his Muslim brother. The entirety of the Muslim is sacred to another Muslim: his life, his wealth, and his honor.

Source: Ṣaḥīḥ Muslim 2564, Grade: Sahih

Abdullah ibn Mas’ud reported: The Prophet, peace and blessings be upon him, said:

لَا يَدْخُلُ الْجَنَّةَ مَنْ كَانَ فِي قَلْبِهِ مِثْقَالُ ذَرَّةٍ مِنْ كِبْرٍ

No one who has the weight of a seed of arrogance in his heart will enter Paradise.

Someone said, “But a man loves to have beautiful clothes and shoes.” The Prophet said:

إِنَّ اللَّهَ جَمِيلٌ يُحِبُّ الْجَمَالَ الْكِبْرُ بَطَرُ الْحَقِّ وَغَمْطُ النَّاسِ

Verily, Allah is beautiful and he loves beauty. Arrogance means rejecting the truth and looking down on people.

Source: Ṣaḥīḥ Muslim 91, Grade: Sahih

Abu Huraira reported: The Messenger of Allah, peace and blessings be upon him, said:

إِذَا قَالَ الرَّجُلُ هَلَكَ النَّاسُ ‏ فَهُوَ أَهْلَكُهُمْ

If a man says the people are ruined, he is the most ruined among them.

Source: Ṣaḥīḥ Muslim 2623, Grade: Sahih

Al-Nawawi commented on this tradition, saying:

وَاتَّفَقَ الْعُلَمَاءُ عَلَى أَنَّ هَذَا الذَّمَّ إِنَّمَا هُوَ فِيمَنْ قَالَهُ عَلَى سَبِيلِ الْإِزْرَاءِ عَلَى النَّاسِ وَاحْتِقَارِهِمْ وَتَفْضِيلِ نَفْسِهِ عَلَيْهِمْ وَتَقْبِيحِ أَحْوَالِهِمْ لِأَنَّهُ لَا يَعْلَمُ سِرَّ اللَّهِ فِي خَلْقِهِ

The scholars agree that this disapproval refers only to those who say it in contempt for people, to denigrate them, to claim themselves superior to them, and to accuse them of evil intentions, for he does not know the secrets of Allah in His creation.

Source: Sharḥ al-Nawawī ‘alá Ṣaḥīḥ Muslim 2623

Jundab reported: The Messenger of Allah, peace and blessings be upon him, said:

أَنَّ رَجُلاً قَالَ وَاللَّهِ لاَ يَغْفِرُ اللَّهُ لِفُلاَنٍ وَإِنَّ اللَّهَ تَعَالَى قَالَ مَنْ ذَا الَّذِي يَتَأَلَّى عَلَىَّ أَنْ لاَ أَغْفِرَ لِفُلاَنٍ فَإِنِّي قَدْ غَفَرْتُ لِفُلاَنٍ وَأَحْبَطْتُ عَمَلَكَ

A man said: By Allah, Allah will not forgive this person! Allah Almighty said: Who is he who swore by me that I will not forgive someone? I have forgiven him and nullified your good deeds.

Source: Ṣaḥīḥ Muslim 2621, Grade: Sahih

‘Uqbah ibn ‘Amir reported: The Messenger of Allah, peace and blessings be upon him, said:

إِنَّ أَنْسَابَكُمْ هَذِهِ لَيْسَتْ بِسِبَابٍ عَلَى أَحَدٍ وَإِنَّمَا أَنْتُمْ وَلَدُ آدَمَ طَفُّ الصَّاعِ لَمْ تَمْلَئُوهُ لَيْسَ لِأَحَدٍ فَضْلٌ إِلَّا بِالدِّينِ أَوْ عَمَلٍ صَالِحٍ حَسْبُ الرَّجُلِ أَنْ يَكُونَ فَاحِشًا بَذِيًّا بَخِيلًا جَبَانًا

Verily, these lineages of yours cannot be used to disparage anyone. You are all the children of Adam, going back to him equally and cannot be exceeded. No one is favored except by religion or good deeds. It is enough sin for a man to be vulgar, shameless, miserly, and cowardly.

Source: Musnad Aḥmad 16978, Grade: Sahih

Abu Dharr reported: The Prophet, peace and blessings be upon him, said:

انْظُرْ فَإِنَّكَ لَيْسَ بِخَيْرٍ مِنْ أَحْمَرَ وَلَا أَسْوَدَ إِلَّا أَنْ تَفْضُلَهُ بِتَقْوَى

Behold! Verily, you have no virtue over one with white skin or black skin, except by favor of righteousness.

Source: Musnad Aḥmad 20885, Grade: Hasan

Jabir ibn Abdullah reported: The Messenger of Allah, peace and blessings be upon him, addressed us during the middle of the day at the end of the pilgrimage in the farewell sermon. The Prophet said:

يَا أَيُّهَا النَّاسُ إِنَّ رَبَّكُمْ وَاحِدٌ وَإِنَّ أَبَاكُمْ وَاحِدٌ أَلا لا فَضْلَ لِعَرَبِيٍّ عَلَى عَجَمِيٍّ وَلا لِعَجَمِيٍّ عَلَى عَرَبِيٍّ وَلا لأَحْمَرَ عَلَى أَسْوَدَ وَلا أَسْوَدَ عَلَى أَحْمَرَ إِلا بِالتَّقْوَى إِنَّ أَكْرَمَكُمْ عِنْدَ اللَّهِ أَتْقَاكُمْ أَلا هَلْ بَلَّغْتُ

O people, your Lord is one and your father Adam is one. There is no virtue of an Arab over a foreigner, nor a foreigner over an Arab, and neither white over black nor black over white, except by righteousness. Have I not delivered the message?

They said, “Of course, O Messenger of Allah.” The Prophet said:

فَلْيُبَلِّغِ الشَّاهِدُ الْغَائِبَ

Let the witness inform those who are absent.

Source: Shu’ab al-Imān 4706, Grade: Sahih li ghayrihi

Abu Huraira reported: The Messenger of Allah, peace and blessings be upon him, said:

مَنْ بَطَّأَ بِهِ عَمَلُهُ لَمْ يُسْرِعْ بِهِ نَسَبُهُ

Whoever is slow to good deeds will not be hastened by his lineage.

Source: Ṣaḥīḥ Muslim 2699, Grade: Sahih

Abu Huraira reported: The Prophet, peace and blessings be upon him, said:

إِنَّ اللَّهَ قَدْ أَذْهَبَ عَنْكُمْ عُبِّيَّةَ الْجَاهِلِيَّةِ وَفَخْرَهَا بِالْآبَاءِ إِنَّمَا هُوَ مُؤْمِنٌ تَقِيٌّ وَفَاجِرٌ شَقِيٌّ النَّاسُ كُلُّهُمْ بَنُو آدَمَ وَآدَمُ خُلِقَ مِنْ تُرَابٍ

Verily, Allah has removed from you the pride of the time of ignorance with its boasting of ancestors. Verily, one is only a righteous believer or a miserable sinner. All of the people are the children of Adam, and Adam was created from dust.

Source: Sunan al-Tirmidhī 3955, Grade: Sahih