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."
Sahih al-Bukhari Book 46, Hadith 5
← Previous Hadith Allah's Messenger (ﷺ) said, "Help your brother, whether he is an oppressor or he is an oppressed one."

Sahih al-Bukhari Book 46, Hadith 4 Next Hadith → I heard Al-Bara' bin `Azib saying, "The Prophet (ﷺ) orders us to do seven things and prohibited us from doing seven other things." Then Al-Bara' mentioned the following:-- (1) To pay a visit to the sick (inquiring about his health), (2) to follow funeral processions, (3) to say to a sneezer, "May Allah be merciful to you" (if he says, "Praise be to Allah!"), (4) to return greetings, (5) to help the oppressed, (6) to accept invitations, (7) to help others to fulfill their oaths. (See Hadith No. 753, Vol. 7)

Sahih al-Bukhari Book 46, Hadith 6