It is narrated from Hazrat Abdur Rahman bin Abzi (may Allah be pleased with him) on the authority of Ubayy bin Ka'b (may Allah be pleased with him) that once the Holy Prophet (peace and blessings be upon him) led us in the Fajr prayer, and during the recitation, he omitted a verse. Hazrat Ubayy had arrived when part of the prayer had already passed. After the prayer, he submitted, "O Messenger of Allah! Has this verse been abrogated, or did you forget it?" The Prophet (peace and blessings be upon him) replied, "No, rather I forgot it."