Sa'id bin Harb al-Abdi said: I was sitting with Sayyiduna Abdullah bin Umar (may Allah be pleased with him) in al-Masjid al-Haram during the time of Sayyiduna Abdullah bin al-Zubayr (may Allah be pleased with him). Under the obedience of Sayyiduna Abdullah bin al-Zubayr (may Allah be pleased with him) were the chiefs of the Khawarij, among them Nafi' bin al-Azraq, Atiyyah bin al-Aswad and Najdah. They sent a man to Sayyiduna Abdullah bin Umar (may Allah be pleased with him) to ask: Why do you not give the pledge of allegiance to Sayyiduna Abdullah bin al-Zubayr (may Allah be pleased with him)? He raised his hand, which was trembling from old age, and said: "By Allah!" I will not give my pledge of allegiance for division, nor will I withhold it from the community.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16809