The Leader of the Muslims
An individual by the name of Jabir or Juwabir states that during the era of Hazrat Umar’s (ra) Khilafat, he went to see Hazrat Umar (ra) in relation to some matter. He states that there was a person who was stood next to Hazrat Umar (ra) who had white hair and was wearing white clothes. The aforementioned individual said, “Verily, the means to attain our objective and the provisions for the hereafter are present in this very world and our deeds in this world shall be rewarded in the hereafter.” Jabir states that he asked, “O Leader of the Faithful, who is this person?” Hazrat Umar (ra) replied, “Ubayy (ra) bin Kaab, the leader of the Muslims.”
(Ibn Saad, Al-Tabaqat al-Kubra, Vol. 3 [Beirut, Lebanon: Dar al-Kutub al-Ilmiyyah, 2017] 378, 379)