The following is a brief explanation of Ayat ul Kursi [verse 2:255 in the Qur’an], which was named the greatest verse in the Qur’an by the Prophet Muhammad (pbuh). The explanation of it below is a translation from Zubdat at-Tafsir, a popular brief Qur’anic exegesis in Arabic by Mohammad Sulayman al-Ashqar.
اللَّهُ لا إِلَهَ إِلا هُوَ الْحَيُّ الْقَيُّومُ لا تَأْخُذُهُ سِنَةٌ وَلا نَوْمٌ لَهُ مَا فِي السَّمَاوَاتِ وَمَا فِي الأَرْضِ مَنْ ذَا الَّذِي يَشْفَعُ عِنْدَهُ إِلا بِإِذْنِهِ يَعْلَمُ مَا بَيْنَ أَيْدِيهِمْ وَمَا خَلْفَهُمْ وَلا يُحِيطُونَ بِشَيْءٍ مِنْ عِلْمِهِ إِلا بِمَا شَاءَ وَسِعَ كُرْسِيُّهُ السَّمَاوَاتِ وَالأَرْضَ وَلا يَئُودُهُ حِفْظُهُمَا وَهُوَ الْعَلِيُّ الْعَظِيمُ
Allah – there is no deity except Him, the Ever-Living, the Sustainer of [all] existence. Neither drowsiness overtakes Him nor sleep. To Him belongs whatever is in the heavens and whatever is on the earth. Who is it that can intercede with Him except by His permission? He knows what is before them and what is behind them, and they encompass not a thing of His knowledge except for what He wills. His Kursi extends over the heavens and the earth, and their preservation tires Him not. And He is the Most High, the Most Great.
< Allah – there is no deity except Him> That there is no deity with the right to worship except Him
<the Ever-Living> Life is opposite of death and [Allah] the Exalted has absolute/perfect life [which is] without end, without change, and without being afflicted with [any type of] defect
<the Sustainer of [all] existence> The One in Charge with disposing [the affairs of] the creation and preserving it
<drowsiness> It is that which precedes sleep due to weakness and the closing of the eyes
<Who is it that can intercede with Him except by His permission> There is no one from among His slaves that is able to bring benefit [either] by interceding to Allah or any other means [except] by Allah [first] permitting the intercessor to intercede
<He knows what is before them> [what is to happen] before them in the afterlife
<and what is behind them> [their deeds] from the world[ly life]
<His Kursi extends> Ibn Abbas narrated: “The Kursi is the place of the two feet.” And Sa’eed bin Jubayr narrated: “His Kursi is His Knowledge” and Tabari preferred it [latter opinion]. And in [another] saying: “The Kursi is the Throne itself”
<and their preservation tires Him not> It means Allah, the Exalted, is not fatigued by preserving the two [heavens and earth] nor does He [ever] face from it [even a] minimal [amount of] hardship
<the Most High> Higher than His creation in His Ascension, His Power and [He is] Victorious, Omnipotent.
And it is narrated in the authentic prophetic tradition that this is the greatest verse in the Qur’an from ‘Ubayy bin Ka’b [who said] that the Prophet (pbuh) asked him, “Which verse do you think is the greatest in the Qur’an?” He [‘Ubayy] replied, “Verse of the Kursi.” [Prophet] said, “Congratulations upon your knowledge O Abu’l-Mundhir.”
And Asmaa’ bint Yazeed said, “I heard the Messenger of Allah (pbuh) say [that] ‘in these two verses: Allah – there is no deity except Him, the Ever-Living [2:255] and Alif Laam Meem. Allah – there is no deity except Him, the Ever-Living [3:1-2] – is the greatest name of Allah.'”