One day, while we were sitting with the Messenger of Allah ﷺ, a man suddenly appeared before us whose clothes were intensely white and whose hair was intensely black. No trace of travel could be seen on him, yet none of us recognized him.He then mentioned the hadith, in which the Prophet ﷺ said, "Umar, do you know who the questioner was?"I replied, "Allah and His Messenger know best."He said, "That was Jibreel. He came to you to teach you your religion."
بينما نحن عند رسول الله ﷺ ذات يوم إذ طلع علينا رجل شديد بياض الثياب، شديد سواد الشعر، لا يرى عليه أثر السفر، ولا يعرفه منا أحد. فذكر الحديث، وفيه: قال النبي ﷺ: يا عمر، أتدري من السائل؟ قلت: الله ورسوله أعلم. قال: فإنه جبريل أتاكم يعلمكم دينكم.
Muslim narrated it in the Book of Faith (8) through various routes from Yahya bin Yamar, from Ibn Umar, from Umar bin Khattab, and he related the hadith in full. See the beginning of the Book of Faith.