Sahih Ibn Khuzaymah

Yahya bin Ya’mar narrates that I and Humaid bin Abdur Rahman set out to perform Hajj and Umrah, so we said, “If we meet any companion of the Messenger of Allah (ﷺ), how good it would be.” Thus, we met Abdullah bin Umar (may Allah be pleased with them both), and he said that Umar (may Allah be pleased with him) narrated a hadith to me. He said: One day while we were sitting in the presence of the Messenger of Allah (ﷺ), suddenly a man appeared whose clothes were extremely white and clean, and whose hair was intensely black and clean, and we did not know him (i.e., he was a stranger, but there were no signs of travel on him). He came close and sat down with his knees touching the Prophet’s knees and placed his hands on his thighs and said, “O Muhammad (ﷺ), tell me about Islam. What is Islam?” The Prophet (ﷺ) said: “(Islam is) that you bear witness that there is no god but Allah and that Muhammad (ﷺ) is the Messenger of Allah, and that you establish prayer, pay zakat, fast in the month of Ramadan, and perform Hajj to the House (Ka’bah) if you are able to find a way to it.” He said, “You have spoken the truth.” Then he narrated the complete hadith.