Hamzah bin Abdullah bin Umar (may Allah have mercy on him) says: I was sitting with Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) when a man from Iraq came and said: By Allah, I have been eager to adopt your way and follow your example in the matter of the people's division, and to keep away from evil as far as I am able. I recite a clear (muhkam) verse from the Book of Allah that has gripped my heart; tell me about it: what is the meaning of Allah's saying: "And if two groups of the believers fight" [Surah al-Hujurat: 9]? Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: What concern is that of yours? Go away. He left, and when he had gone out of sight, Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) turned to us and said: I have not felt anything in my heart about the affairs of this Ummah as I have felt that I did not fight this transgressing group as Allah Almighty commanded me. Hamzah (may Allah have mercy on him) says: We said: Which transgressing group? He said: Ibn al-Zubayr (may Allah be pleased with them both) transgressed against these people, broke his covenant with them, and drove them out of their homes.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16706