Imam Ahmad recorded that Asma' bint Yazid bin As-Sakan said, "I heard the Messenger of Allah say about these two Ayat,

﴿اللَّهُ لاَ إِلَـهَ إِلاَّ هُوَ الْحَىُّ الْقَيُّومُ ﴾

(Allah! None has the right to be worshipped but He, the Ever Living, the One Who sustains and protects all that exists) ﴿2:255﴾, and,

﴿الم - ذَلِكَ الْكِتَابُ لاَ رَيْبَ فِيهِ هُدًى لِّلْمُتَّقِينَ ﴾

(Alif-Lam-Mim. Allah! None has the right to be worshipped but He, the Ever Living, the One Who sustains and protects all that exists) ﴿3:1-2﴾,

«إِنَّ فِيهِمَا اسْمَ اللهِ الْأَعْظَم»

(They contain Allah's Greatest Name.)

This is also the narration collected by Abu Dawud, At-Tirmidhi and Ibn Majah, and At-Tirmidhi said, "Hasan Sahih''.

Further, Ibn Marduwyah recorded that Abu Umamah reported that the Prophet said,

«اسْمُ اللهِ الْأَعْظَمُ، الَّذِي إِذَا دُعِيَ بِهِ أَجَابَ، فِي ثَلَاثٍ: سُورَةِ الْبَقَرَةِ وَآلِ عِمْرَانَ وَطه»

(Allah's Greatest Name, if He was supplicated with it, He answers the supplication, is in three Surahs - Al-Baqarah, Al `Imran and Ta-Ha.)

Hisham bin `Ammar, the Khatib (orator) of Damascus (one of the narrators in the above narration), said, "As for Al-Baqarah, it is in,

﴿اللَّهُ لاَ إِلَـهَ إِلاَّ هُوَ الْحَىُّ الْقَيُّومُ ﴾

(Allah! None has the right to be worshipped but He, the Ever Living, the One Who sustains and protects all that exists) ﴿2:255﴾; in Al `Imran, it is in,

﴿الم - ذَلِكَ الْكِتَابُ لاَ رَيْبَ فِيهِ هُدًى لِّلْمُتَّقِينَ ﴾

(Alif-Lam-Mim. Allah! None has the right to be worshipped but He, the Ever Living, the One Who sustains and protects all that exists) ﴿3:1-2﴾, while in Ta-Ha, it is in,

﴿وَعَنَتِ الْوُجُوهُ لِلْحَىِّ الْقَيُّومِ﴾

(And (all) faces shall be humbled before (Allah), the Ever Living, the One Who sustains and protects all that exists) ﴿20:111﴾.''