Ubayy bin Ka’b (radi Allahu anhu) reported: “The Messenger of Allah (ﺳﻴﺪﻧﺎ ﻣﺤﻤﺪ ﺻﻠﯽ ﺍﻟﻠﻪ ﺗﻌﺎﻟﯽٰ ﻋﻠﯿﮧ ﻭﺍٓﻟﮧ ﻭﺳﻠﻢ) said: ‘Abu Mundhir! Do you know which Ayat in Allah’s Book is the greatest?‘ I said: ‘Allah and His Messenger know best.‘ He (sal Allahu alaihi wa sallam) again said: ‘Do you know which Ayat in Allah’s Book, according to you, is the greatest?‘ I (Abu Mundhir) replied: ‘It is ‘Allah la ilaha illa Huwal-Hayyul-Qayyum…” [2:255] Thereupon, he (sal Allahu alaihi wa sallam) patted me on the chest and said, ‘Rejoice by your knowledge, O Abu Mundhir!‘ (i.e, may this knowledge be a source of respect, honour and benefit to you).” [Sahih Muslim]
The reason that Ayat al-Kursi is the most excellent Ayat (verse) is that it mentions the names of Allah Most High more than any other Ayat does, thus it contains the most remembrance (dhikr) of Allah Most High. In Ayat al-Kursi, the names of Allah Most High have been mentioned seventeen times. Ayat al-Kursi mentions six attributes (sifaat) of Allah Most High, all six being mentioned in this single Ayat. 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).
Regarding Ayat al-Kursi and the last two Ayaat of Surah Baqarah, Shaytan said that since these three ayaat were revealed it became difficult for the devils to remain in Madina. No doubt it was because of people’s frequent recitation of these great Ayaat. Not only are these recited at bed time, but Ayat al-Kursi was recited by the Messenger of Allah (sal Allahu alaihi wa sallam) after each Fardh prayer too.
Ali ibn Abu Talib (radi Allahu anhu) narrates, “I cannot understand how a person, who is a Muslim, and owner of reason (intellect) can spend the night without reading Ayat al-Kursi. If you knew the benefits of it, then you would never discard under any condition“.