AYAT-ul-Kursi (Qur’an, 2:255) is the most magnificent verse of the Qur’an.
Ubayy Bin Ka’b says once the Prophet (peace be upon him) asked me, “O Abu Mundhir, do you know which verse of the Qur’an with you is the most magnificent?” I submitted: “Allah-o-la-illaaha illa huwal-hayyul Qaiyum…” (2:255).
The Prophet (peace be upon him) thumped my chest as a gesture of appreciation and said: “Congratulations on your knowledge (of the Qur’an), O Abu Mundhir!” (Sahih Muslim)
Abu Hurairah narrates:
Prophet Mohammed (peace be upon him) appointed me to guard the Sadqa Fitr (alms given during Ramadan before Eid). One night an intruder came and started collecting the food. I caught hold of him and said: “I will produce you before the Prophet (peace be upon him)” but the intruder pleaded: “I am a poor man and have number of children to support. I am badly in need of help and succor.” On hearing this woeful tale I let him go.
In the morning the Prophet (peace be upon him) asked me: “Abu Hurairah what happened to your thief last night?” I answered, “O Messenger of Allah! He pleaded his dire necessity and complained about his large family. As such I felt pity for him and let him go.” The Prophet (peace be upon him) remarked: “He has lied, he will come back again.”
I was sure he would come again as the Prophet (peace be upon him) had said, and therefore I kept watch and waited for him. The thief did come again and started gathering food. I caught him again and said that I would definitely take him to the Prophet (peace be upon him).
On this he requested that he was a needy person and had a large family to support and that he may be let off and promised that he would not come back. I felt pity for him once more and let him go.
Next morning the Prophet (peace be upon him) asked: “Abu Hurairah what about your prisoner of last night? I answered: “O Messenger of Allah, he pleaded his dire necessity and the fact that he had a large family, and therefore I felt pity for him and let him go.” He (peace be upon him) said: “He told you a lie and will come back again!”
So I maintained a watch for him a third time. He did come to steal food (from the alms store) Abu Hurairah says: “I caught hold of him and said; I shall certainly take you to the Prophet (peace be upon him) and this is the last of the three times you promised that you will not come back, (but you have broken your promise and came back).”
He pleaded: “Please let me go and I will in return teach you some phrases which will bring benefit and mercy from Allah.” I asked him: “What are those?” He said: “When you go to bed (during night) recite the verse (Ayat-ul-Kursi, 2:255). (As a result of its blessings) Allah will appoint a guard to protect you, and Satan will not be able to come near to you till morning.”
So I allowed him to go. Next morning when I visited the Prophet (peace be upon him) he asked me: “What did you do with your prisoner last night?” I said, “O Messenger of Allah, he said that he would teach me some phrases through which I would receive benefit and mercy of Allah. On this I let him go.” He (peace be upon him) asked, “What are those phrases?” I said: “He told me, when you go to your bed for sleep, recite the verse ‘Ayat-ul-Kursi’ from beginning to end, and told me that Allah would post a guard on me and Satan would not be able to come near me till the morning.”
The Prophet (peace be upon him) said: “This time he told you the truth although he is a liar. Abu Hurairah, do you know with whom you were speaking during these three nights?” I answered; “No.” The Prophet (peace be upon him) said: “It was Satan (the devil).”
Prophet Mohammed (peace be upon him) also said that whoever recites Ayat-ul-Kursi after every Fardh (obligatory) Salah, nothing can keep him away from entering Paradise except death. (Al-Bukhari)