Narrated Abu Sa`id bin Al-Mu'alla:

While I was praying in the Mosque, Allah's Messenger (ﷺ) called me but I did not respond to him. Later I said, "O Allah's Messenger! I was praying." He said, "Didn't Allah say'--"Give your response to Allah (by obeying Him) and to His Apostle when he calls you." (8.24) He then said to me, "I will teach you a Sura which is the greatest Sura in the Qur'an, before you leave the Mosque." Then he got hold of my hand, and when he intended to leave (the Mosque), I said to him, "Didn't you say to me, 'I will teach you a Sura which is the greatest Sura in the Qur'an?' He said, "Al-Hamdu-Li l-lah Rabbi-l-`alamin (i.e. Praise be to Allah, the Lord of the worlds) which is Al-Sab'a Al-Mathani (i.e. seven repeatedly recited Verses) and the Grand Qur'an which has been given to me."

Narrated Abu Sa`id Al-Mu'alla:

While I was praying, the Prophet (ﷺ) called me but I did not respond to his call. Later I said, "O Allah's Apostle! I was praying." He said, "Didn't Allah say: 'O you who believe! Give your response to Allah (by obeying Him) and to His Apostle when he calls you'?" (8.24) He then said, "Shall I not teach you the most superior Surah in the Qur'an?" He said, '(It is), 'Praise be to Allah, the Lord of the worlds. ' (i.e., Surat Al-Fatiha) which consists of seven repeatedly recited Verses and the Magnificent Qur'an which was given to me."

Narrated Abu Sa`id bin Al-Mu'alla:

While I was praying, Allah's Messenger (ﷺ) passed me and called me, but I did not go to him until I had finished the prayer. Then I went to him, and he said, "What prevented you from coming to me? Didn't Allah say:-- "O you who believe! Answer the call of Allah (by obeying Him) and His Apostle when He calls you?" He then said, "I will inform you of the greatest Sura in the Qur'an before I leave (the mosque)." When Allah's Messenger (ﷺ) got ready to leave (the mosque), I reminded him. He said, "It is: 'Praise be to Allah, the Lord of the worlds.' (i.e. Surat-al-Fatiha) As-sab'a Al-Mathani (the seven repeatedly recited Verses).

Narrated Abu Sa`id Al-Mualla:

While I was praying, the Prophet (ﷺ) passed by and called me, but I did not go to him till I had finished my prayer. When I went to him, he said, "What prevented you from coming?" I said, "I was praying." He said, "Didn't Allah say" "O you who believes Give your response to Allah (by obeying Him) and to His Apostle." (8.24) Then he added, "Shall I tell you the most superior Sura in the Qur'an before I go out of the mosque?" When the Prophet (ﷺ) intended to go out (of the Mosque), I reminded him and he said, "That is: "Al hamdu-li l-lahi Rabbil-`alamin (Surat-al-fatiha)' which is the seven oft repeated verses (Al-Mathani) and the Grand Qur'an which has been given to me."