It is narrated from Sayyiduna Abu Sa'id Mu'alla that once I was praying, and by chance, the Prophet (peace and blessings of Allah be upon him) passed by. He called out to me, but I did not come to him until I had completed my prayer. After that, I went to him, and the Prophet (peace and blessings of Allah be upon him) said: "What prevented you from coming to me?" I replied: "I was praying." The Prophet (peace and blessings of Allah be upon him) said: "Did Allah not say: 'O you who believe! Respond to Allah and to the Messenger when he calls you to that which gives you life'?" Then he said: "Shall I not teach you the greatest Surah of the Noble Qur'an before you leave the mosque?" Then, when the Prophet (peace and blessings of Allah be upon him) was about to leave the mosque, I reminded him. The Prophet (peace and blessings of Allah be upon him) said: "It is Surah Al-Fatihah. It is the seven oft-repeated verses, and it is the Great Qur'an which has been given to me."