Musnad Ahmad 998:1

Hassan ibn Musa narrated to us, Ibn Lahi'ah narrated to us, Zuhrah—meaning Ibn Ma'bad ibn Abdullah ibn Hisham, Abu Aqil—narrated to us, from his grandfather, who said: I was with the Messenger of Allah, may Allah bless him and grant him peace, and he was holding the hand of Umar ibn al-Khattab. Umar said: "By Allah, O Messenger of Allah, you are more beloved to me than everything except my own self." The Messenger of Allah, may Allah bless him and grant him peace, said: "No, by the One in Whose hand is my soul, until I am more beloved to you than your own self." Umar then said: "So now, by Allah, you are more beloved to me than my own self." The Messenger of Allah, may Allah bless him and grant him peace, said: "Now, O Umar."