Sahih al-Bukhari 2444
Book 46: Oppressions · Narrated by Anas
Arabic
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا مُعْتَمِرٌ، عَنْ حُمَيْدٍ، عَنْ أَنَسٍ ـ رضى الله عنه ـ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " انْصُرْ أَخَاكَ ظَالِمًا أَوْ مَظْلُومًا ". قَالُوا يَا رَسُولَ اللَّهِ هَذَا نَنْصُرُهُ مَظْلُومًا، فَكَيْفَ نَنْصُرُهُ ظَالِمًا قَالَ " تَأْخُذُ فَوْقَ يَدَيْهِ ".
English translation
Narrated Anas:Allah's Messenger (ﷺ) said, "Help your brother, whether he is an oppressor or he is an oppressed one. People asked, "O Allah's Messenger (ﷺ)! It is all right to help him if he is oppressed, but how should we help him if he is an oppressor?" The Prophet (ﷺ) said, "By preventing him from oppressing others
Reference: Sahih al-Bukhari 2444, Book of Oppressions. English translation by Dr. Muhammad Muhsin Khan.