The qualities needed to enjoin good and forbid evil

Sufyan al-Thawri, may Allah have mercy on him, said:

لا يَأْمُرُ بِالْمَعْرُوفِ وَلا يَنْهَى عَنِ الْمُنْكَرِ إِلا مَنْ كَانَ فِيهِ خِصَالٌ ثَلاثٌ رَفِيقٌ بِمَا يَأْمُرُ رَفِيقٌ بِمَا يَنْهَى عَدْلٌ بِمَا يَأْمُرُ عَدْلٌ بِمَا يَنْهَى عَالِمٌ بِمَا يَأْمُرُ عَالِمٌ بِمَا يَنْهَى

There is no enjoining good or forbidding evil except for one who has three qualities: gentleness in what he enjoins and forbids, justice in what he enjoins and forbids, and knowledge of what he enjoins and forbids.

al-Amr bil-Maʻrūf lil-Khallāl 32

Enjoining good and forbidding evil الأمر بالمعروف والنهي عن المنكر

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