مَنْ رَأَى مِنْكُمْ مُنْكَرًا فَلْيُغَيِّرْهُ بِيَدِهِ فَإِنْ لَمْ يَسْتَطِعْ فَبِلِسَانِهِ فَإِنْ لَمْ يَسْتَطِعْ فَبِقَلْبِهِ وَذَلِكَ أَضْعَفُ الْإِيمَانِ
Whoever among you sees evil, let him change it with his hand. If he is unable to do so, then with his tongue. If he is unable to do so, then with his heart, and that is the weakest level of faith.
Ṣaḥīḥ Muslim 49, Grade: Sahih
Hadith on Oppression: Allah has forbidden injustice for Himself
On the authority of Abu Dharr al-Ghifaree (may Allah be pleased with him) from the Prophet (peace and blessings of Allah be upon him) from his Lord, that He said:
O My servants! I have forbidden dhulm (oppression) for Myself, and I have made it forbidden amongst you, so do not oppress one another. O My servants, all of you are astray except those whom I have guided, so seek guidance from Me and I shall guide you. O My servants, all of you are hungry except those whom I have fed, so seek food from Me and I shall feed you. O My servants, all of you are naked except those whom I have clothed, so seek clothing from Me and I shall clothe you. O My servants, you commit sins by day and by night, and I forgive all sins, so seek forgiveness from Me and I shall forgive you. O My servants, you will not attain harming Me so as to harm Me, and you will not attain benefiting Me so as to benefit Me. O My servants, if the first of you and the last of you, and the humans of you and the jinn of you, were all as pious as the most pious heart of any individual amongst you, then this would not increase My Kingdom an iota. O My servants, if the first of you and the last of you, and the humans of you and the jinn of you, were all as wicked as the most wicked heart of any individual amongst you, then this would not decrease My Kingdom an iota. O My servants, if the first of you and the last of you, and the humans of you and the jinn of you, were all to stand together in one place and ask of Me, and I were to give everyone what he requested, then that would not decrease what I Possess, except what is decreased of the ocean when a needle is dipped into it. O My servants, it is but your deeds that I account for you, and then recompense you for. So he who finds good, let him praise Allah, and he who finds other than that, let him blame no one but himself.
Sahih Muslim 2577a
Islam, faith, and excellence الإسلام والإيمان والإحسان
Umar ibn al-Khattab reported: We were sitting with the Messenger of Allah, peace and blessings be upon him, one day when a man appeared with very white clothes and very black hair. There were no signs of travel on him and we did not recognize him. He sat down in front of the Prophet and rested his knees by his knees and placed his hands on his thighs. The man said, “O Muhammad, tell me about Islam.” The Prophet said:
الْإِسْلَامُ أَنْ تَشْهَدَ أَنْ لَا إِلَهَ إِلَّا اللَّهُ وَأَنَّ مُحَمَّدًا رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَتُقِيمَ الصَّلَاةَ وَتُؤْتِيَ الزَّكَاةَ وَتَصُومَ رَمَضَانَ وَتَحُجَّ الْبَيْتَ إِنْ اسْتَطَعْتَ إِلَيْهِ سَبِيلًا
Islam is to testify there is no God but Allah and Muhammad is the Messenger of Allah, to establish prayer, to give charity, to fast the month of Ramadan, and to perform pilgrimage to the House if a way is possible.
The man said, “You have spoken truthfully.” We were surprised that he asked him and then said he was truthful. He said, “Tell me about faith.” The Prophet said:
أَنْ تُؤْمِنَ بِاللَّهِ وَمَلَائِكَتِهِ وَكُتُبِهِ وَرُسُلِهِ وَالْيَوْمِ الْآخِرِ وَتُؤْمِنَ بِالْقَدَرِ خَيْرِهِ وَشَرِّهِ
Faith is to believe in Allah, His angels, His books, His messengers, the Last Day, and to believe in providence, its good and its evil.
The man said, “You have spoken truthfully. Tell me about excellence.” The Prophet said:
أَنْ تَعْبُدَ اللَّهَ كَأَنَّكَ تَرَاهُ فَإِنْ لَمْ تَكُنْ تَرَاهُ فَإِنَّهُ يَرَاكَ
Excellence is to worship Allah as if you see Him, for if you do not see Him, He surely sees you.
Ṣaḥīḥ Muslim 8, Grade: Sahih
Taken from the Forty Hadith al-Nawawi, Hadith 2