Ayat al-Kursi is a single verse, Quran 2:255, yet Muslim tradition sets it above every other passage in the book. In a narration preserved in Sahih Muslim, the Prophet asks his companion Ubayy ibn Ka'b which verse of God's book is greatest, and when Ubayy answers that it is the Throne Verse, the Prophet congratulates him on his knowledge. The verse itself is a compressed theology.
God is introduced by the two names al-Hayy and al-Qayyum, the Living and the Self-Subsisting, and the verse then walks through his attributes, that neither slumber nor sleep overtakes him, that everything in the heavens and the earth belongs to him, that no one intercedes with him except by his permission, that he knows what lies before and behind his creatures while they grasp nothing of his knowledge except what he wills. At its centre sits the image that gives the verse its name, the kursi, throne or footstool, which extends over the heavens and the earth, whose keeping does not weary him. Commentators have read the kursi variously, some as a created reality distinct from the throne proper, others as a figure for God's knowledge or sovereignty, a debate carried through the classical commentaries without ever disturbing the verse's devotional standing.