Allah calls Himself An-Nur—The Light, The Illuminating— on one occasion in the Quran. He is the one who is the light and from whom comes all light. An-Nur is the light of the heavens and earth, and His light clarifies and reveals, both physically and spiritually!
The Light, The One who reveals and illuminates
An-Nur comes from the root noon-waw-raa which points to four main meanings. The first main meaning is to give light and illuminate and the second to make visible, reveal,, and clarify. The third main meaning is to be flaming, blazing, and apparent to the senses, and the fourth main meaning to enlighten or give advice.
This root appears 194 times in the Quran in three derived forms. Examples of these forms are an-naara (the Fire), nuruhum (their light) and muneerah (illuminating).
Linguistically, nur is used to indicate anything that gives off light, in the form of rays for example, and is that which makes things visible. Referring to Allah ‘azza wa jall, He is the one by whom everything is made visible, whose attribute is light, and He is the One who illuminates (munawwir) and the One who guides (Haadi) the heavens and the earth!
An-Nur Himself says: Allah is the Light of the heavens and the earth. [Quran, 24:35]
The essence of Light
In the Quran and Sunnah we can find that Allah ‘azza wa jall has a nur (light) related to Him as an attribute of His essence. This is the same as His other attributes, for example sight, knowledge, might, etc. An-Nur says: And the earth will shine with the Light of its Rabb. [Quran, 39:69] This refers to the magnificent moment Allah ‘azza wa jall will come on the Day of Resurrection to judge mankind.
The Prophet salallahu ‘alayhi wa sallam stated about Allah’s attribute of nur: You are the Light of the heavens and the earth.[Al-Bukhaaree] He salallahu ‘alayhi wa sallam also said the very weighty words: Light is His hijaab (veil), if He uncovers it then the subuhaat (brightness and splendour) of His Face would burn His creation so far as His Sight reaches. [Muslim]