Silsilat al-Ahadith al-Sahihah

Abu Harb bin Abu Aswad says: I was present with Sayyiduna Ali and Sayyiduna Zubair (may Allah be pleased with them). Sayyiduna Zubair (may Allah be pleased with him) was returning, cutting through the ranks on his mount. His son, Sayyiduna Abdullah (may Allah be pleased with him), came before him and asked: "What has happened to you?" He replied: "Sayyiduna Ali (may Allah be pleased with him) has narrated to me a hadith which I myself heard from the Messenger of Allah (peace and blessings be upon him). He (peace be upon him) said: 'You will certainly fight him, and you will be the oppressor against him.' So I will not fight him." Sayyiduna Abdullah (may Allah be pleased with him) said: "Have you come to fight? You have come to reconcile between the people. Perhaps Allah, the Exalted, will settle this matter through you." He said: "I have sworn an oath not to fight." Sayyiduna Abdullah said: "(As expiation) free the slave named Jarjas and remain here until reconciliation is made between the people." So he freed his slave Jarjas and stayed there, but when the matter among the people became disputed (and reconciliation could not be achieved), he mounted his horse and left.