Musannaf Ibn Abi Shayba 3:5799

Abu Mu'awiyah narrated to us, from al-A'mash, from Ibrahim, from 'Abd al-Rahman ibn Yazid, who said: 'Uthman prayed four [rak'ahs] in Mina. So 'Abdullah [ibn Mas'ud] said: "I prayed with the Prophet, may Allah bless him and grant him peace, in Mina two rak'ahs, and with Abu Bakr two rak'ahs, and with 'Umar two rak'ahs. Then the paths diverged for you. I wish that I had, out of the four rak'ahs, two accepted rak'ahs."