Musannaf Ibn Abi Shayba 33:217

Abu Khalid al-Ahmar narrated to us, from Yahya ibn Sa'id, from al-Qasim, from Aslam, the freed slave of Umar, who said: When we arrived in al-Sham with Umar, he made his camel kneel and went to relieve himself. I threw my fur cloak between the two pommels of the saddle. When he came, he mounted upon the fur. We met the people of al-Sham who were coming to receive Umar, and they began to look. I began to gesture to them toward him. He said: Umar said, "Their eyes are straining toward the mounts of those who have no share [in the Hereafter]." He meant the mounts of the non-Arabs.