It is reported from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) that when the Messenger of Allah (peace and blessings be upon him) passed away, the speakers of the Ansar stood up. One of them began to say: "O company of Muhajirun! Whenever the Prophet (peace and blessings be upon him) appointed a man from among you as an official, he paired with him a man from us, so we think that two men should take charge of this matter, one from you and one from us." All the speakers (of the Ansar) followed in support of this. Then Sayyiduna Zayd bin Thabit (may Allah be pleased with him) stood up and said: "the Prophet (peace and blessings be upon him) himself was from the Muhajirun, and the Imam will be from the Muhajirun, and we will be his helpers just as we were the helpers of the Messenger of Allah (peace and blessings be upon him)." Sayyiduna Abu Bakr (may Allah be pleased with him) stood up and said: "May Allah reward you with good, O Ansar, and keep your speaker firm." Then he said: "Had you done otherwise, we would not have come to terms with you." Then Sayyiduna Zayd bin Thabit (may Allah be pleased with him) took the hand of Abu Bakr and said: "This is your man, so pledge allegiance to him." Then they went off. When Sayyiduna Abu Bakr (may Allah be pleased with him) sat on the pulpit, he looked at the faces of the people and did not see Sayyiduna Ali (may Allah be pleased with him). He asked about him, and some people of the Ansar got up and brought him. Sayyiduna Abu Bakr (may Allah be pleased with him) said: "The cousin of the Messenger of Allah (peace and blessings be upon him) and his son-in-law! Did you want to break the unity of the Muslims?" Sayyiduna Ali (may Allah be pleased with him) said: "No blame (upon you), O Khalifah of the Messenger of Allah," and he pledged allegiance to him. Then he did not see Sayyiduna al-Zubayr bin al-Awwam (may Allah be pleased with him); he asked about him until they brought him, and he said: "The son of the paternal aunt of the Messenger of Allah (peace and blessings be upon him) and his disciple (hawari)! Did you want to break the unity of the Muslims?" He said the like of what Ali had said: "No blame (upon you), O Khalifah of the Messenger of Allah," and both of them pledged allegiance to Sayyiduna Abu Bakr (may Allah be pleased with him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16538