Musnad Ahmad Hadith 21095

It is narrated from Abu Huraira (may Allah be pleased with him) with reference to Ubayy bin Ka'b (may Allah be pleased with him) that the Holy Prophet (ﷺ) said: "Shall I not teach you a Surah the like of which is not found in the Torah, the Psalms, the Gospel, nor even in the Qur'an itself?" I said, "Why not?" The Holy Prophet (ﷺ) said, "I hope that you will not leave through this door until you have learned it." Then the Holy Prophet (ﷺ) stood up and I stood up with him. The Holy Prophet (ﷺ) took my hand and began to talk to me, and as we walked, we reached near the door. I reminded the Holy Prophet (ﷺ) and said, "O Messenger of Allah! Please tell me the Surah about which you spoke to me." The Holy Prophet (ﷺ) said, "When you stand to pray, what do you recite?" He recited Surah Al-Fatiha. The Holy Prophet (ﷺ) said, "That is the Surah. That is the Seven Oft-Repeated (verses), and that is the Great Qur'an which has been given to me."