It was narrated that Abu Umaamah (ra) said: “The Messenger of Allah (peace and blessings of Allah be upon him) said: “Whoever recites Aayat al-Kursiy immediately after each prescribed prayer, there will be nothing standing between him and his entering Paradise except death.”
Ubayy bin Ka’b (radiAllahu anhu) reported: The Messenger of Allah (peace be upon him) said: “Abu Mundhir! Do you know which Ayah in Allah’s Book is the greatest? I said: ‘Allah and His messenger know best.’
He (peace be upon him) again said: ‘Do you know which Ayah 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 (peace be upon him) patted me in 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)’.”
Abu Dhar said; O Messenger of Allah, what is the greatest thing that has been revealed to you?’ He said, Ayat al-Kursi, ‘Allah! La ilaha illa Huwa’
When you lie down in your bed, recite ayat al-Kursi, Allah! La ilaha illa Huwa (none has the right to be worshipped but He), the Ever Living, the One Who sustains and protects all that exists… [al-Baraqah 2:255] until the end of the ayah, then you will have a protector from Allah and no shaytan (devil) will come near you until morning comes