Anas ibn Mālik (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: “Support your brother whether he is an oppressor or oppressed.” A man said: "O Messenger of Allah, I should support him if he is oppressed, but how should I support him if he is an oppressor?" The Prophet (may Allah's peace and blessings be upon him) said: “Support him by preventing him from practicing oppression.” Authentic hadith - Narrated by Bukhari