Musnad Ahmad 26:876

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Sulayman, who said: I heard 'Umarah ibn 'Umayr, or Ibrahim—Shu'bah was uncertain—narrating from 'Abd al-Rahman—that is, Ibn Yazid—from 'Abdullah, that he said: "I prayed with the Prophet, peace and blessings of Allah be upon him, at Mina two rak'ahs, and with Abu Bakr, and with 'Umar. So, may my share of the four rak'ahs be two accepted rak'ahs."