Musannaf Ibn Abi Shayba 34:11

Qabisah narrated to us, from Sufyan, from Asim ibn Kulayb, from his father, from Khalid ibn Arfatah, who said: The first time I saw the disagreement of the companions of Muhammad was when Uthman entered into the state of ihram for Hajj, and Ali entered into the state of ihram for Hajj and Umrah.