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

الترهيب من الظلم ودعاء المظلوم وخذله والترغيب في نصرته

Warning against oppression, the supplication of the oppressed, and forsaking them, and encouragement to support them.

Source: al-Targhīb wal-Tarhīb 3/183

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

قال الله تبارك وتعالى يَا عِبَادِي إِنِّي حَرَّمْتُ الظُّلْمَ عَلَى نَفْسِي وَجَعَلْتُهُ بَيْنَكُمْ مُحَرَّمًا فَلَا تَظَالَمُوا

Allah Almighty said: O My servants, I have forbidden injustice for Myself and I have forbidden it among you, so do not oppress one another.

Source: Ṣaḥīḥ Muslim 2577, Grade: Sahih

Jabir ibn Abdullah reported: The Messenger of Allah, peace and blessings be upon him, said:

اتَّقُوا الظُّلْمَ فَإِنَّ الظُّلْمَ ظُلُمَاتٌ يَوْمَ الْقِيَامَةِ وَاتَّقُوا الشُّحَّ فَإِنَّ الشُّحَّ أَهْلَكَ مَنْ كَانَ قَبْلَكُمْ حَمَلَهُمْ عَلَى أَنْ سَفَكُوا دِمَاءَهُمْ وَاسْتَحَلُّوا مَحَارِمَهُمْ

Beware of committing oppression, for oppression will be darkness on the Day of Resurrection. Beware of greed, for greed ruined those before you. It caused them to shed their blood and to make lawful what was unlawful to them.

Source: Ṣaḥīḥ Muslim 2578, Grade: Sahih

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

إِنَّ الظُّلْمَ ظُلُمَاتٌ يَوْمَ الْقِيَامَةِ

Verily, oppression will be darkness on the Day of Resurrection.

Source: Ṣaḥīḥ al-Bukhārī 2447, Grade: Muttafaqun Alayhi 

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

إِيَّاكُمْ وَالظُّلْمَ فَإِنَّ الظُّلْمَ ظُلُمَاتٌ عِنْدَ اللَّهِ يَوْمَ الْقِيَامَةِ وَإِيَّاكُمْ وَالْفُحْشَ فَإِنَّ اللَّهَ لَا يُحِبُّ الْفُحْشَ وَالتَّفَحُّشَ وَإِيَّاكُمْ وَالشُّحَّ فَإِنَّهُ دَعَا مَنْ قَبْلَكُمْ فَاسْتَحَلُّوا مَحَارِمَهُمْ وَسَفَكُوا دِمَاءَهُمْ وَقَطَّعُوا أَرْحَامَهُمْ

Beware of committing injustice, for injustice will be darkness on the Day of Resurrection. Beware of obscenity, for Allah does not love obscenity and immorality. Beware of greed, for it tempted those before you and caused them to make lawful what is unlawful, to shed blood and sever their family ties.

Source: Musnad Aḥmad 9569, Grade: Sahih

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

صِنْفَانِ مِنْ أُمَّتِي لَنْ تَنَالَهُمَا شَفَاعَتِي إِمَامٌ ظَلُومٌ وَكُلُّ غَالٍ مَارِقٍ

Two kinds of people from my nation will never receive my intercession: an oppressive and malevolent leader, and every extremist renegade.

Source: al-Mu’jam al-Kabīr lil-Ṭabarānī 8079, Grade: Hasan

Ibn Umar reported: The Prophet, peace and blessings be upon him, said:

الْمُسْلِمُ أَخُو الْمُسْلِمِ لَا يَظْلِمُهُ وَلَا يَخْذُلُ وَالَّذِي نَفْسُ مُحَمَّدٍ بِيَدِهِ مَا تَوَادَّ اثْنَانِ فَفُرِّقَ بَيْنَهُمَا إِلَّا بِذَنْبٍ يُحْدِثُهُ أَحَدُهُمَا

The Muslims is the brother of another Muslim. He does not wrong him, nor forsake him. By the One in whose hand is the soul of Muhammad, no two people who love each other for Allah and then separate but that it was due to a sin committed by one of them.

Source: Musnad Aḥmad 5357, Grade: Sahih

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

مَا تَوَادَّ اثْنَانِ فِي اللَّهِ جَلَّ وَعَزَّ أَوْ فِي الإِسْلامِ فَيُفَرِّقُ بَيْنَهُمَا إِلا بِذَنْبٍ يُحْدِثُهُ أَحَدُهُمَا

No two people loved one another for the sake of Allah Almighty, or for Islam, then separated from one another but that it was due to a sin one of them committed.

Source: al-Adab al-Mufrad lil-Bukhārī 401, Grade: Sahih

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

إِنَّ اللَّهَ لَيُمْلِي لِلظَّالِمِ حَتَّى إِذَا أَخَذَهُ لَمْ يُفْلِتْهُ

Verily, Allah Almighty will give respite to the wrongdoer until He seizes him and they cannot escape.

Then, the Prophet (s) recited the verse:

وَكَذَلِكَ أَخْذُ رَبِّكَ إِذَا أَخَذَ الْقُرَى وَهِيَ ظَالِمَةٌ إِنَّ أَخْذَهُ أَلِيمٌ شَدِيدٌ

Such is the seizure of your Lord, when He takes hold of the cities while they are doing wrong. Verily, His seizure is agonizing and severe. (11:102)

Source: Ṣaḥīḥ al-Bukhārī 4686, Grade: Muttafaqun Alayhi

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

إِنَّ الشَّيْطَانَ قَدْ يَئِسَ أَنْ تُعْبَدَ الْأَصْنَامُ فِي أَرْضِ الْعَرَبِ وَلَكِنَّهُ سَيَرْضَى مِنْكُمْ بِدُونِ ذَلِكَ بِالْمُحَقِّرَاتِ وَهِيَ الْمُوبِقَاتُ يَوْمَ الْقِيَامَةِ اتَّقُوا الْمَظَالِمَ مَا اسْتَطَعْتُمْ فَإِنَّ الْعَبْدَ يَجِيءُ بِالْحَسَنَاتِ يَوْمَ الْقِيَامَةِ يَرَى أَنَّهُ سَتُنْجِيهِ فَمَا زَالَ عَبْدٌ يَقُومُ فَيَقُولُ يَا رَبِّ ظَلَمَنِي عَبْدُكَ مَظْلَمَةً فَيَقُولُ امْحُوا مِنْ حَسَنَاتِهِ مَا يَزَالُ كَذَلِكَ حَتَّى مَا يَبْقَى لَهُ حَسَنَةٌ مِنَ الذُّنُوبِ وَإِنَّ مِثْلَ ذَلِكَ كَسَفْرٍ نَزَلُوا بِفَلَاةٍ مِنَ الْأَرْضِ لَيْسَ مَعَهُمْ حَطَبٌ فَتَفَرَّقَ الْقَوْمُ لِيَحْتَطِبُوا فَلَمْ يَلْبَثُوا أَنْ حَطَبُوا فَأَعْظَمُوا النَّارَ وَطَبَخُوا مَا أَرَادُوا وَكَذَلِكَ الذُّنُوبُ

Verily, Satan has despaired that idols will be worshipped in the land of the Arabs, but rather he will be pleased with you for less than that by your contempt for each other, which is a punishment on the Day of Resurrection. Guard against acts of wrongdoing as much as you can, for a servant will come with good deeds on the Day of Resurrection that he thinks will save him. Another servant will stand and continue to say: O Lord, Your servant has done great wrong to me! It will be said: Erase his good deeds! Such will continue until no good deeds compare to his many sins. Verily, the parable of that is like a traveler who settles in a desert among the lands with no firewood, so the people disperse from him in search of firewood and before long they find it and kindle a large fire to cook whatever they wish. Such is the way of sins.

Source: Musnad Abī Ya’lá 5122, Grade: Sahih li ghayrihi

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

أَتَدْرُونَ مَا الْمُفْلِسُ

Do you know who are bankrupt?

They said, “The one without money or goods is bankrupt.” The Prophet said:

إِنَّ الْمُفْلِسَ مِنْ أُمَّتِي يَأْتِي يَوْمَ الْقِيَامَةِ بِصَلَاةٍ وَصِيَامٍ وَزَكَاةٍ وَيَأْتِي قَدْ شَتَمَ هَذَا وَقَذَفَ هَذَا وَأَكَلَ مَالَ هَذَا وَسَفَكَ دَمَ هَذَا وَضَرَبَ هَذَا فَيُعْطَى هَذَا مِنْ حَسَنَاتِهِ وَهَذَا مِنْ حَسَنَاتِهِ فَإِنْ فَنِيَتْ حَسَنَاتُهُ قَبْلَ أَنْ يُقْضَى مَا عَلَيْهِ أُخِذَ مِنْ خَطَايَاهُمْ فَطُرِحَتْ عَلَيْهِ ثُمَّ طُرِحَ فِي النَّارِ

Verily, the bankrupt of my nation are those who come on the Day of Resurrection with prayers, fasting, and charity, but also with insults, slander, consuming wealth, shedding blood, and beating others. The oppressed will each be given from his good deeds. If his good deeds run out before justice is fulfilled, then their sins will be cast upon him and he will be thrown into the Hellfire.

Source: Ṣaḥīḥ Muslim 2581, Grade: Sahih

Mu’adh ibn Jabal reported: The Messenger of Allah, peace and blessings be upon him, said:

وَاتَّقِ دَعْوَةَ الْمَظْلُومِ فَإِنَّهُ لَيْسَ بَيْنَهَا وَبَيْنَ اللَّهِ حِجَابٌ

Beware the supplication of the oppressed, for there is no veil between it and Allah.

Source: Ṣaḥīḥ al-Bukhārī 4347, Grade: Muttafaqun Alayhi

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

ثَلَاثُ دَعَوَاتٍ مُسْتَجَابَاتٌ لَا شَكَّ فِيهِنَّ دَعْوَةُ الْمَظْلُومِ وَدَعْوَةُ الْمُسَافِرِ وَدَعْوَةُ الْوَالِدِ عَلَى وَلَدِهِ

Three supplications are answered without a doubt: the supplication of an oppressed person, the supplication of a traveler, and the supplication of a parent over his child.

Source: Sunan al-Tirmidhī 1905, Grade: Hasan

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

ثَلَاثٌ مُسْتَجَابٌ لَهُمْ دَعْوَتُهُمْ الْمُسَافِرُ وَالْوَالِدُ وَالْمَظْلُومُ

The supplications of three people are answered: the traveler, the parents, and the oppressed.

Source: Musnad Aḥmad 17399, Grade: Hasan li ghayrihi

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

اتَّقُوا دَعَوَاتِ الْمَظْلُومِ فَإِنَّهَا تَصْعَدُ إِلَى السَّمَاءِ كَأَنَّهَا شَرَارٌ

Beware of the supplication of the oppressed, for it ascends to the heavens as if it were a flare.

Source: al-Mustadrak ‘alá al-Ṣaḥīḥayn 81, Grade: Sahih

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

دَعْوَةُ الْمَظْلُومِ مُسْتَجَابَةٌ وَإِنْ كَانَ فَاجِرًا فَفُجُورُهُ عَلَى نَفْسِهِ

The supplication of the oppressed is answered, even if he is wicked, for his wickedness is only against himself.

Source: Musnad Aḥmad 8795, Grade: Hasan

Khuzaymah ibn Thabit reported: The Messenger of Allah, peace and blessings be upon him, said,

اتَّقُوا دَعْوَةَ الْمَظْلُومِ فَإِنَّهَا تُحْمَلُ عَلَى الْغَمَامِ يَقُولُ اللَّهُ جَلَّ جَلالُهُ وَعِزَّتِي وَجَلالِي لأَنْصُرَنَّكَ وَلَوْ بَعْدَ حِينٍ

Beware of the supplication of the oppressed, for it is carried above the clouds. Allah Almighty says: By My might and majesty, I will help you in due time.

Source: al-Mu’jam al-Kabīr lil-Ṭabarānī 3718, Grade: Sahih

Anas ibn Malik reported: The Messenger of Allah, peace and blessings be upon him, said:

اتَّقُوا دَعْوَةَ الْمَظْلُومِ وَإِنْ كَانَ كَافِرًا فَإِنَّهُ لَيْسَ دُونَهَا حِجَابٌ

Beware of the supplication of the oppressed, even if he is an unbeliever, for there is nothing to block it.

Source: Musnad Aḥmad 12549, Grade: Hasan

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

لَا تَحَاسَدُوا وَلَا تَنَاجَشُوا وَلَا تَبَاغَضُوا وَلَا تَدَابَرُوا وَلَا يَبِعْ بَعْضُكُمْ عَلَى بَيْعِ بَعْضٍ وَكُونُوا عِبَادَ اللَّهِ إِخْوَانًا الْمُسْلِمُ أَخُو الْمُسْلِمِ لَا يَظْلِمُهُ وَلَا يَخْذُلُهُ وَلَا يَحْقِرُهُ التَّقْوَى هَاهُنَا

Do not envy each other, do not outbid each other, do not hate each other, do not turn away from each other, and do not outsell each other. Rather, be servants of Allah as brothers. The Muslim is the brother of another Muslim. He does not wrong him, nor humiliate him, nor look down upon him. Righteousness is here,

And the Prophet (s) pointed to his chest three times, then he 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 reputation.

Source: Ṣaḥīḥ Muslim 2564, Grade: Sahih

Abu Dharr reported: I said, “O Messenger of Allah, instruct me.” The Prophet, peace and blessings be upon him, said:

أَوْصَيْكَ بِتَقْوَى اللَّهِ عَزَّ وَجَلَّ فَإِنَّهُ أَزْيَنُ لأَمْرِكَ كُلِّهِ

I advise you to fear Allah Almighty, for it will beautify all of your affairs.

I said, “Tell me more.” The Prophet (s) said:

عَلَيْكَ بِتِلاوَةِ الْقُرْآنِ وَذِكْرِ اللَّهِ عَزَّ وَجَلَّ فَإِنَّهُ ذِكْرٌ لَكَ فِي السَّمَاءِ وَنُورٌ لَكَ فِي الأَرْضِ

You must recite the Quran and remember Allah Almighty, for you will be mentioned in heaven and you will have light upon the earth.

I said, “Tell me more.” The Prophet (s) said:

عَلَيْكَ بِطُولِ الصَّمْتِ فَإِنَّهُ مَطْرَدَةٌ لِلشَّيْطَانِ وَعَوْنٌ لَكَ عَلَى أَمْرِ دِينِكَ

You must observe long periods of silence, for it will drive away Satan and help you in the matter of your religion.

I said, “Tell me more.” The Prophet (s) said:

إِيَّاكَ وَكَثْرَةَ الضَّحِكِ فَإِنَّهُ يُمِيتُ الْقَلْبَ وَيَذْهَبُ بِنُورِ الْوَجْهِ

Beware of too much laughter, for it will deaden the heart and take away the light on your face.

I said, “Tell me more.” The Prophet (s) said:

قُلِ الْحَقَّ وَإِنْ كَانَ مُرًّا

Speak the truth, even if it is bitter.

I said, “Tell me more.” The Prophet (s) said:

لا تَخَفْ فِي اللَّهِ لَوْمَةَ لائِمٍ

Do not fear the blame of any critic in the matter of Allah.

Source: Shu’ab al-Imān 4592, Grade: Sahih li ghayrihi

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

أُمِرَ بِعَبْدٍ مِنْ عِبَادِ اللهِ أَنْ يُضْرَبَ فِي قَبْرِهِ مِائَةَ جَلْدَةٍ فَلَمْ يَزَلْ يَسْأَلُ وَيَدْعُو حَتَّى صَارَتْ جَلْدَةً وَاحِدَةً فَجُلِدَ جَلْدَةً وَاحِدَةً فَامْتَلَأَ قَبْرُهُ عَلَيْهِ نَارًا فَلَمَّا ارْتَفَعَ عَنْهُ قَال عَلَامَ جَلَدْتُمُونِي قَالُوا إِنَّكَ صَلَّيْتَ صَلَاةً بِغَيْرِ طُهُورٍ وَمَرَرْتَ عَلَى مَظْلُومٍ فَلَمْ تَنْصُرْهُ

One of the servants of Allah was commanded to be flogged in his grave with a hundred lashings. He continued to beg and plead until it was reduced to a single lashing, then his grave became filled with fire. When it was taken away from him, he said: May I know why you flogged me? It will be said: You performed prayer without ablution, and when you passed by an oppressed person, you did not help him.

Source: Sharḥ Mushkil al-Āthār 3185, Grade: Hasan

Anas ibn Malik reported: The Messenger of Allah, peace and blessings be upon him, said:

انْصُرْ أَخَاكَ ظَالِمًا أَوْ مَظْلُومًا

Help your brother, whether he is an oppressor or is being oppressed.

It was said, “O Messenger of Allah, we help the oppressed, but how do we help an oppressor?” The Prophet said:

تَأْخُذُ فَوْقَ يَدَيْهِ

By seizing his hand.

Source: Ṣaḥīḥ al-Bukhārī 2444, Grade Muttafaqun Alayhi

Jabir ibn Abdullah reported: Two young men were fighting, one from the Muhajirin and one man from the Ansar. The Muhajir called out, “O Muhajirin!” And the Ansari called out, “O Ansar!” The Messenger of Allah, peace and blessings be upon him, came out and he said:

مَا هَذَا دَعْوَى أَهْلِ الْجَاهِلِيَّةِ

What is this call of the people of ignorance?

They said, “O Messenger of Allah, it is only two boys fighting and one had kicked the other.” The Prophet (s) said:

فَلاَ بَأْسَ وَلْيَنْصُرِ الرَّجُلُ أَخَاهُ ظَالِمًا أَوْ مَظْلُومًا إِنْ كَانَ ظَالِمًا فَلْيَنْهَهُ فَإِنَّهُ لَهُ نَصْرٌ وَإِنْ كَانَ مَظْلُومًا فَلْيَنْصُرْهُ ‏

No matter, let a man help his brother whether he is wrong or being wronged. If he is oppressing others, then stop him, for that is supporting him. If he is being oppressed, then support him.”

Source: Ṣaḥīḥ Muslim 2584, Grade: Sahih