Suuratul – Baqarah Verse 255.
ٱللَّـهُ لَآ إِلَـٰهَ إِلَّا هُوَ ٱلْحَىُّ ٱلْقَيُّومُ ۚ لَا تَأْخُذُهُۥ سِنَةٌ وَلَا نَوْمٌ ۚلَّهُۥ مَا فِى ٱلسَّمَـٰوَٰتِ وَمَا فِى ٱلْأَرْضِ ۗ
مَن ذَا ٱلَّذِى يَشْفَعُ عِندَهُۥٓ إِلَّا بِإِذْنِهِۦ ۚ يَعْلَمُ مَا بَيْنَ أَيْدِيهِمْ وَمَا خَلْفَهُمْ ۖ وَلَا يُحِيطُونَ بِشَىْءٍ مِّنْ عِلْمِهِۦٓ إِلَّا بِمَا شَآءَ ۚ
وَسِعَ كُرْسِيُّهُ ٱلسَّمَـٰوَٰتِ وَٱلْأَرْضَ ۖ وَلَا يَـُٔودُهُۥ حِفْظُهُمَا ۚ وَهُوَ ٱلْعَلِىُّ ٱلْعَظِيمُ ﴿٢٥٥
255. Allah! La ilaha illa Huwa, the Ever Living, the One Who sustains and protects all that exists. Neither slumber, nor sleep overtake Him. To Him belongs whatever is in the heavens and whatever is on earth. Who is he that can intercede with Him except with His Permission? He knows what happens to them (His creatures) in this world, and what will happen to them in the Hereafter . And they will never compass anything of His Knowledge except that which He wills. His Kursi extends over the heavens and the earth, and He feels no fatigue in guarding and preserving them. And He is the Most High, the Most Great. [This Verse is called Ayat-ul-Kursi]
Tafsir Ibn Kathir Volume 2, Page 24.
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) 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) that
«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, the Ever Living, the One Who sustains and protects all that exists (20:111).”