(3) CHAPTER. The Statement of Allah: “And indeed, We have bestowed upon you seven Al-Mathani (i.e., seven repeatedly recited Verses i.e., Surat Al-Fatiha) and the Grand Quran.” (V.15:87)
Narrated Abu Sa`id Al-Mualla: While I was praying, the Prophet 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 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.
Narrated Abu Huraira: Allah's Messenger said, The Um (substance) of the Qur'an is the seven oft-repeated verses (Al- Mathaini) and is the Great Qur'an (i.e. Surat-al-Fatiha).