The Outside

"When they were born, their sheer brilliance alone caused the empty to warp and morph and be reborn alongside them, resulting in the creation of the first realm, the eternal realm - Ein Sof, the Land of God."

- Brahma

The Ein Sof, also known as The Outside or the Paradoxical Space, is the divine and most ancient realm that ever exists outside of Creation, encompassing it in its totality.

It is beyond the Four Worlds and is the halo of the Adam Kadmon.

Summary
Ein Sof is the divine and primordial that was formed when the Celestial Princes were created as their brilliance accidentally gave birth to it. However, it neither is nor isn't an Olam (עוֹלָם‎; "World" or "Eon") as such a term cannot be applied to the Ein Sof.

In this realm, duality, space, time, infinite, finite, life, death, existence, and nonexistence are absolutely meaningless, nullified by the very presence of God and can only be a maybe as dictated by God or the Celestial Princes themselves. It is referred to as "The Outside" or "The Realm of Everything and Nothing" as it is a realm where the concept of Nothingness is made manifest.

It is a place beyond time, space, void, fate, and death, freed from all restrictions and constraints that are within even the core essence of Adam Kadmon. It is the background collective unity that lies beyond Creation which is merely a mere infinitesimal blip within its entirety.

Despite its titles, it cannot be described as the highest form because the realm exists beyond definition.

Realms

 * Purgatorium: More commonly known as Purgatory, this is a primordial realm created by the Celestial Prince Samael to serve as the new home-realm to the Fallen Angels and the Grigori's main base of operation. It also serves as an intermediate state after one's physical death for expiatory purification, where a soul who dies virtuously but still imperfectly purified will achieve the holiness necessary to enter Shamayim.
 * Shamayim: More commonly known as the Abrahamic Heavens or just simply Heaven, this is the first realm of the Ein Sof, created by the Abrahamic God to be the home-realm for Them and Their angelic creations. It is also where those who die of the utmost righteous and virtuous deaths will ascend upon, living in absolute ecstasy and bliss for the rest of eternity as rewards for their fruitful life.
 * Sheol: More commonly known as the Abrahamic Underworld or Hell, this is the primordial realm created by the Abrahamic God to serve as the new home-realm for Lucifer and his followers in the Heavenly War, having greatly opposed the divine authority of God and the Heavenly Council and were banished from Shamayim because of it. It is also where the souls of those who have committed the worst of sins and crimes in their life will be banished to and are damned to be subjected to punitive sufferings and torture as eternal punishment after death.

Quotes
"Any name of God which is found in the Bible can not be applied to the Deity prior to His self-manifestation in the Creation, because the letters of those names were produced only after the emanation... Moreover, a name implies a limitation in its bearer; and this is impossible in connection with the "Ein Sof"."

- Minḥat Yehudah

"Before He gave any shape to the world, before He produced any form, He was alone, without form and without resemblance to anything else. Who then can comprehend how He was before the Creation? Hence it is forbidden to lend Him any form or similitude, or even to call Him by His sacred name, or to indicate Him by a single letter or a single point... But after He created the form of the Heavenly Man, He used him as a chariot wherein to descend, and He wishes to be called after His form, which is the sacred name "YHWH""

- Zohar

Trivia

 * Despite what many people believed, the Ein Sof is implied to possibly be older than the Celestial Princes themselves.
 * Gabriel stated that it was God's gift to them, being created in celebration of their creation.
 * Uriel once said it was for more older than them, with possibly the exceptions of Michael and Lucifer, and might be as ancient as God Themself.
 * The realm is implied to possess some form of consciousness.
 * According to Azazel, Ein Sof could be likened to the library of which the shelves of Adam Kadmon are contained.
 * Ein Sof in Kabbalah is the state God was in prior to self-manifestation. The term was first used by Azriel of Gerona, one of the most important Kabbalists at that time, who held Neoplatonic beliefs and thought that God can have no thought, no desire, or action as all of these are negated by it. It is the origin of the Ohr Ein Sof (The Divine Infinite Light).
 * In Lurianic Kabbalah, the Tzimtzum (Self-Withdrawal), which is the first act of Creation, takes place within the Ein Sof to create an empty void from which all of Creation springs from.
 * Ein Sof springs from the concept of Ayin, which is the Nonexistence beyond Nonexistence and Existence and cannot be defined. In the Tzimtzum's order of de-evolution into our physical creation, Ein Sof is defined as 00.