Musannaf Ibn Abi Shayba 3:1484

Yahya ibn Sa'id narrated to us, from Ubaydullah, from Nafi', from Ibn Umar, from Umar; and Sufyan, from Zayd ibn Aslam, from his father, from Amr; and from Shu'bah, from al-Hakam, from Ibrahim, from al-Aswad, from Umar: That he prayed two rak'ahs in Makkah, then said: "We are a traveling people, so complete the prayer."