Musnad Abu Ya'la al-Mawsili 42:113

Uthman narrated to us, Jarir narrated to us, from al-A'mash, from Isma'il ibn Raja', from his father, from Abu Sa'id al-Khudri, who said: I heard the Messenger of Allah (ﷺ) saying: "Indeed, among you is one who will fight for the interpretation (ta'wil) of the Qur'an, just as I fought for its revelation (tanzil)." Abu Bakr said: "Is it I, O Messenger of Allah?" He said: "No." Umar said: "Is it I, O Messenger of Allah?" He said: "No, but it is the one who is mending the sandal." And he had given Ali his sandal to mend.