Musnad Abi Ya'la 205 — when he was wounded (in the assassination)

It is narrated from Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) that when he was wounded (in the assassination attack), Sayyiduna Abdullah bin Umar (may Allah be pleased with him) said to him: "O Commander of the Believers, will you not appoint someone as your successor (caliph)?" He (may Allah be pleased with him) said: "I do not find anyone more deserving of this office than those men with whom the Messenger of Allah (peace and blessings be upon him) was pleased at the time of his death." Then he named Sayyiduna Ali, Sayyiduna Uthman, Sayyiduna Talhah, Sayyiduna al-Zubayr, Sayyiduna Abd al-Rahman bin Awf and Sayyiduna Sa'd bin Abi Waqqas (may Allah be pleased with them), and said: "Sayyiduna Abdullah bin Umar (may Allah be pleased with him) will be present with them (as a witness), but he will have no share in the matter of the caliphate. So whomever these men choose as successor, he will be the caliph after me. Then if the caliphate comes to Sayyiduna Sa'd (may Allah be pleased with him), (well and good); otherwise, whoever becomes caliph after me should seek his help and counsel, for I did not remove him (from the governorship) because of any weakness or dishonesty."