One of the greatest gifts that we have been given by Allah [SWT] is that of Ayatul Kursi (the Verse of the Footstool). It is verse 255 in Surah Baqarah (2). Here are some of it’s virtues:
- A Guarantee of Paradise
“The one who recites it after each of the obligatory prayers, then death will be the only thing [i.e. barrier] preventing him from entering al-Jannah.” 
- The Prophet described it as the greatest ayah in the Quran. 
- In it the Most Great Name of Allah (ismullahi al-’atham) is mentioned. 
- It protects from the shayatin (devils). 
- The believer who recites it following an obligatory salah is under the Care and Protection of Allah until the commencement of the next prayer. 
- It is the only place in the Quran where the Kursi (Footstool of Allah) is mentioned.
اللّهُ لاَ إِلَـهَ إِلاَّ هُوَ الْحَيُّ الْقَيُّومُ لاَ تَأْخُذُهُ سِنَةٌ وَلاَ نَوْمٌ لَّهُ مَا فِي السَّمَاوَاتِ وَمَا فِي الأَرْضِ مَن ذَا الَّذِي يَشْفَعُ عِنْدَهُ إِلاَّ بِإِذْنِهِ يَعْلَمُ مَا بَيْنَ أَيْدِيهِمْ وَمَا خَلْفَهُمْ وَلاَ يُحِيطُونَ بِشَيْءٍ مِّنْ عِلْمِهِ إِلاَّ بِمَا شَاء وَسِعَ كُرْسِيُّهُ السَّمَاوَاتِ وَالأَرْضَ وَلاَ يَؤُودُهُ حِفْظُهُمَا وَهُوَ الْعَلِيُّ الْعَظِيمُ
Allah! None has the right to be worshiped but He, the Ever Living, the One Who sustains and protects all that exists. Neither slumber, nor sleep overtake Him. To Him belongs whatever is in the heavens and whatever is on earth. Who is he that can intercede with Him except with His Permission? He knows what happens to them (His creatures) in this world, and what will happen to them in the Hereafter. And they will never compass anything of His Knowledge except that which He wills. His Footstool extends over the heavens and the earth, and He feels no fatigue in guarding and preserving them. And He is the Most High, the Most Great.
The Messenger of Allah [SAWS] said: “Whoever recites Ayatul Kursi immediately after each prescribed (obligatory) prayer, there will be nothing standing between him and his entering Paradise except death.”
[Reported by An-Nasa’i and Ibn Hibban]
Ubayy bin Ka’b [RA] reported:
The Messenger of Allah [SAWS] said, “Abu Mundhir (Ubayy bin Ka’b)! Do you know which Ayah in Allah’s Book is the greatest?
I said, “Allah and His messenger know best.”
He [SAWS] 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 [SAWS] 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).”
Asma’ bint Yazid (radiAllahu anhu) reported:
I heard the Messenger of Allah (peace be upon him) say about these two following Ayahs, i.e, verses: “Allah! There is no god but He – the Living, The Self-subsisting, Eternal. [2:255], And, Alif Lam Mim, Allah! There is no god but He – the Living, The Self-subsisting, Eternal [3:1-2], That they contain Allah’s Greatest Name.”
[Imam Ahmed bin Hanbal in his Musnad]
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Footnotes 13 and 14 in the following article: http://www.islaam.net/main/display.php?id=615&category=4