Musnad Ahmad 298:4

Sufyan ibn 'Uyaynah narrated to us, from Ayyub, from Humayd ibn Hilal, from Hisham ibn 'Amir, who said: "You indeed go to people who are not more knowledgeable of the hadith of the Messenger of Allah (peace and blessings of Allah be upon him) than we are. My father was killed on the day of Uhud, and the Messenger of Allah (peace and blessings of Allah be upon him) said: 'Dig, widen, and bury two or three in the grave, and put forward the one among them who knew the most Quran.'" And my father was the one among them who knew the most Quran, so they put him forward.