Mishkat al-Masabih

Ibn ‘Umar told that God's Messenger stood up, i.e. on the day of Badr, and said, ‘Uthman has gone off on the business of God and His Messenger and I shall take the oath of allegiance on his behalf. God’s Messenger then appointed him a share, but did not do so for anyone else who was absent. Abu Dawud transmitted it.