Literally meaning to separate, abstract, peel away, or to isolate oneself from every occupation and engagement, tajrid (isolation) denotes the state where one isolates oneself from worldly things and abandons all carnal or bodily desires. It also denotes turning away from all else save God and being freed from any attachment to wealth, status or position or any worldly expectations, and setting one’s heart totally on Him without expecting anything in return.
The scholars relate isolation to the Qur’anic statement, Take off your shoes (20:12), and interpret this as the purifying of the heart, which they call the home of God, of all worldly and otherworldly considerations, and preparing it for the visit of the All-Holy Sovereign. Some go a step further and regard this as turning to the Light of Lights with all one’s heart and setting one’s heart totally on Him without leaving any room for anything else in one’s feelings, according to one’s capacity. From another perspective, isolation has been approached as resistance against all carnal or bodily appetites and impulses and against the attractions of the world with whatever is in it. Initiates who have not been able to isolate themselves from carnal appetites, the attractions of the world, the attachment of the heart to anything else save Him, or from any worldly or otherworldly consideration, cannot attain His private company and the spiritual pleasure inherent in this.
Concerning this significant point, the author of al-Minhaj
So long as you do not isolate yourself
from considerations about everything save Him,
You will not be able to reach privacy
with the Beloved in His private room.
Ibrahim Haqqi expresses the same point, as follows:
The heart is the home of God;
purify it of whatever is there other than Him,
So that the All-Merciful may descend into His palace at nights.
Isolation, which, in the words of Sayyid Sharif , is cleaning the heart and other innermost faculties from the dirt and dust of attachment to anything save Him, requires that the people favored with a vision of Him should isolate themselves from whatever they see or hear, and that they live immersed in the lights of the Existence of the Eternal Witness. Every initiate feels this and is favored with its gifts according to the individual’s capacity.
When those who are in the initial stages of the spiritual journey find themselves growing in the knowledge of God that is developing in the heart, the information acquired concerning Him gradually fades, and they begin to receive glimpses from beyond things. Then all of their material or bodily necessities, and even the entire world with whatever is in it, gradually lose their importance and value for them and they become polished mirrors to the truth, or function as some misty medium to reflect Him. One who feels this favor sometimes says, like Fuduli,
The way of isolation is a home
requiring full renunciation and sacrifice to settle in,
so abandon whatever worldly things you have,
and do not have a house.
or sometimes cries, like Yunus Emre:
I have found the unique, matchless honey;
Let everybody come and plunder my existence.
One who has reached the final point of the spiritual journey is freed from all considerations concerning other existent beings save God, and is left with no trace that belongs to anything else except Him. If those favored with this degree of isolation do not follow the principles of the Prophetic way or the rules of Shari‘a in their considerations, they may lapse into negating the “reality of things”— the established originals or essences of things in God’s Knowledge. This is a rank where many initiates live in a daze. Whereas, those who strictly follow the signposts and lights of the Prophetic way during their entire journey, though admitting the reality of things, see in everything only He Who is the One, only know the One, only mention the One, only call the One, and only turn to the One in thousands of signs of “dawn,” turning their eyes from all others.
Ahmedi  describes this rank according to his feeling as follows:
I have submitted all my being to that Friend, having no home any longer;
And purified my hands of any worldly things I had, being left without both of the two worlds.
For God’s love has come and drawn me to itself: opening the eyes of my heart, awakening me from an intoxicated sleep.
His Unity has become manifest to me, so that I have seen Him with all certainty.
I have driven away polytheism, having no doubt any longer.
As for the state of those who have completed their journey toward God, it is such a deep, indescribable state of pleasure, where efforts toward isolation have ended in perfect isolation and they have all but lost their own being, that those who do not experience it cannot know or describe it. Anybody who attempts to describe it cannot be saved from confusion. Such a relation between the Almighty, Ultimate Truth and an initiate whom He has favored with such a degree of spiritual attainment must be a mysterious gift of secrecy of His to His distinguished servants. What we should do is to feel respect for this gift of secrecy.
O God! Show us the truth as being true and enable us to follow it, and show us falsehood as being false and enable us to refrain from it. And bestow blessings and peace on our master Muhammad, the guide to the truth, and on his Family and Companions, godly, noble and honorable.