Sahih Bukhari 4474

حَدَّثَنَا مُسَدَّدٌ , حَدَّثَنَا يَحْيَى , عَنْ شُعْبَةَ , قَالَ : حَدَّثَنِي خُبَيْبُ بْنُ عَبْدِ الرَّحْمَنِ , عَنْ حَفْصِ بْنِ عَاصِمٍ , عَنْ أَبِي سَعِيدِ بْنِ الْمُعَلَّى ، قَالَ : كُنْتُ أُصَلِّي فِي الْمَسْجِدِ ، فَدَعَانِي رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَلَمْ أُجِبْهُ ، فَقُلْتُ : يَا رَسُولَ اللَّهِ ، إِنِّي كُنْتُ أُصَلِّي ، فَقَالَ : أَلَمْ يَقُلِ اللَّهُ اسْتَجِيبُوا لِلَّهِ وَلِلرَّسُولِ إِذَا دَعَاكُمْ لِمَا يُحْيِيكُمْ سورة الأنفال آية 24 ، ثُمَّ قَالَ لِي : لَأُعَلِّمَنَّكَ سُورَةً هِيَ أَعْظَمُ السُّوَرِ فِي الْقُرْآنِ قَبْلَ أَنْ تَخْرُجَ مِنَ الْمَسْجِدِ ، ثُمَّ أَخَذَ بِيَدِي ، فَلَمَّا أَرَادَ أَنْ يَخْرُجَ ، قُلْتُ لَهُ : أَلَمْ تَقُلْ لَأُعَلِّمَنَّكَ سُورَةً هِيَ أَعْظَمُ سُورَةٍ فِي الْقُرْآنِ ؟ قَالَ : الْحَمْدُ لِلَّهِ رَبِّ الْعَالَمِينَ سورة الفاتحة آية 2 هِيَ السَّبْعُ الْمَثَانِي ، وَالْقُرْآنُ الْعَظِيمُ الَّذِي أُوتِيتُهُ .

Narrated Abu Sa`id bin Al-Mu'alla: While I was praying in the Mosque, Allah's Messenger 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.