Musnad Ahmad 603:0

Narrated by Abdullah ibn Hisham, the grandfather of Zahrah ibn Ma'bad: We were with the Prophet (peace and blessings of Allah be upon him), and he was holding the hand of Umar ibn al-Khattab. Umar said to him, "O Messenger of Allah, you are dearer to me than everything except my own self." The Prophet (peace and blessings of Allah be upon him) said, "No, by the One in Whose hand is my soul, until I am dearer to you than your own self." Umar then said to him, "Indeed, now—by Allah—you are dearer to me than my own self." The Prophet (peace and blessings of Allah be upon him) said, "Now, O Umar."