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

(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,

(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),

(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,

(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,

(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,

(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,

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