It is reported that Hazrat Ali (radhiyallahu ‘anhu) once said, “I heard Rasulullah (sallallahu ‘alaihi wasallam) mention the following from the mimbar, ‘The one who recites Aayatul Kursi after every fardh salaah – the only thing that prevents him from entering Jannah is death, and the one who recites Aayatul Kursi when he goes to bed, Allah Ta‘ala will grant him safety over his household, the house of his neighbor and the other houses around him.” (Shu’ab-ul-Imaan #2174)
It is mentioned that Hazrat Ali (radhiyallahu ‘anhu) was punctual on reciting Aayatul Kursi before sleeping and he ensured that he recited it every night when retiring to bed. Hazrat Ali (radhiyallahu ‘anhu) himself mentioned, “I cannot understand how a person, who reaches the age of understanding while he is a Muslim, can go to bed at night without reciting the following verse of the Qur’aan Majeed.” Saying that, Hazrat Ali (radhiyallahu ‘anhu) explained the verse he was referring to by reciting Aayatul Kursi.
Hazrat Ali (radhiyallahu ‘anhu) thereafter said, “If you knew that (great reward and great benefit) which it contains, you would never leave reciting it under any circumstance. Indeed Rasulullah (sallallahu ‘alaihi wasallam) said, ‘I was given Aayatul Kursi from a treasure beneath the throne of Allah Ta‘ala, and it was not given to any Nabi before me.’”
Hazrat Ali (radhiyallahu ‘anhu) then remarked, “From the time I heard this from Rasulullah (sallallahu ‘alaihi wasallam), I never went to bed without reciting Aayatul Kursi.”
(Jaami-ul-Ahaadeeth #34743, Kanz-ul-Ummaal #4059 and Du‘aa li-Tabraani #276)