Theme and Subject-Matter of Surat al-Baqarah, Ayah 255:
The merits of Ayat al-Kursi have been mentioned in numerous hadiths. Although the Quran itself and every verse therein are of excellence, Ayat al-Kursi is certainly the most excellent verse of all its verses. This verse is called Ayat al-Kursi due to the word "Kursi" being mentioned in it.
Of all the chapters in the Quran, the most excellent chapter is Surat al-Ikhlas, and the most excellent verse is Ayat al-Kursi. One virtue of Ayat al-Kursi is that more reward is obtained for reading it than any other verse.
The reason why Ayat al-Kursi is the most excellent verse, is that this verse mentions the names of Allah Most High more than any other verse (i.e. this verse contains the most remembrance (dhikr) of Allah Most High). For example, some verses of the Quran may mention the names of Allah Most High two times, some may mention the names of Allah Most High four times, and some ten times. But in Ayat al-Kursi, the names of Allah Most High have been mentioned seventeen times. Ayat al-Kursi mentions six attributes (sifat) of Allah Most High, all six being mentioned in this single verse. The attributes mentioned are: the Divine Oneness (Wahdaniyyah) of Allah Most High, His Life (Hayah), His Knowledge ('Ilm), His Kingdom (Mulk), His Divine Power (Qudrah) and His Will (Iradah).
Imam Muslim writes that Ubayy bin Ka'b (Allah be well pleased with him) narrated that one day, the Prophet () asked "O Ubayy! What is the most excellent verse of the Quran?" Ubayy replied, "Allah and His Messenger know best." The Prophet (Allah bless him and give him peace) said, "In your opinion, what is the most excellent verse of the Quran?" Ubayy bin Ka'b replied, "Allah - There is no god but He" (i.e. Ayat al-Kursi). The Prophet (a) placed his hand on his chest and said, "O Ubayy bin Ka'b! May your knowledge be pleasant for you." [Sahih Muslim]
Allah's Messenger (a) said: "Whoever recites Ayat al-Kursi at the end of every obligatory prayer, nothing but death will prevent him from entering Paradise." [An-Nasa'i]
