Musnad Ahmad 367, 368

Muhammad ibn Ja‘far narrated to us; Kahmas narrated to us, from Ibn Buraydah. Yazid ibn Harun narrated to us; Kahmas narrated to us, from Ibn Buraydah, from Yahya ibn Ya‘mar, who heard Ibn ‘Umar say: ‘Umar ibn al-Khattab, may Allah be pleased with him, related to me: One day, while we were with Allah’s Prophet, peace and blessings be upon him, a man appeared before us, with intensely white clothes and intensely black hair. He did not appear to have any traces of travel—Yazid said, “We could see no traces of travel on him”—and none of us knew him. He sat close to the Prophet, placed his knees against the Prophet’s knees, and rested his palms on his thighs. He said, “O Muhammad, tell me about Islam. What is Islam?” He replied, “Islam is that you testify there is no god but Allah and that Muhammad is the Messenger of Allah; establish prayer; give zakah; fast Ramadan; and make pilgrimage to the House if you are able to find a way.” He said, “You have spoken truthfully.” We were astonished that he asked him and then affirmed him. He said, “Tell me about faith.” He replied, “Faith is that you believe in Allah, His angels, His Books, His messengers, the Last Day, and the whole of divine decree, its good and its evil.” He said, “You have spoken truthfully.” He said, “Tell me about excellence in worship. What is it?” Yazid said: He replied, “That you worship Allah as if you see Him; and if you do not see Him, then indeed He sees you.” He said, “Tell me about the Hour.” He replied, “The one asked about it knows no more than the one asking.” He said, “Tell me about its signs.” He replied, “That a slave woman gives birth to her mistress, and that you see the barefoot, naked shepherds of sheep competing in building.” Then he left. He said: Some time passed—Yazid said, “Three days”—and the Messenger of Allah, peace and blessings be upon him, said to me, “O ‘Umar, do you know who the questioner was?” I said, “Allah and His Messenger know best.” He said, “That was Gabriel. He came to you to teach you your religion.” ‘Abd Allah ibn Yazid narrated to us; Kahmas narrated to us, from ‘Abd Allah ibn Buraydah, from Yahya ibn Ya‘mar, who heard Ibn ‘Umar say: ‘Umar, may Allah be pleased with him, related to us: We were sitting with the Messenger of Allah, peace and blessings be upon him, and he mentioned the report, except that it said, “No traces of travel were visible on him.” It also says: ‘Umar said, “I waited three [days],” and the Messenger of Allah said to me, “O ‘Umar…”’