Anas ibn Malik reported: The Messenger of Allah, peace and blessings be upon him, said, “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, “By seizing his hand.”
Source: Ṣaḥīḥ al-Bukhārī 2444
Grade: Sahih (authentic) according to Al-Bukhari
عَنْ أَنَسٍ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ انْصُرْ أَخَاكَ ظَالِمًا أَوْ مَظْلُومًا قَالُوا يَا رَسُولَ اللَّهِ هَذَا نَنْصُرُهُ مَظْلُومًا فَكَيْفَ نَنْصُرُهُ ظَالِمًا قَالَ تَأْخُذُ فَوْقَ يَدَيْهِ
2444 صحيح البخاري كتاب المظالم انصر أخاك ظالما أو مظلوما