When the Event Inevitable cometh to pass,
Then will no (soul) entertain falsehood concerning its coming.
Many will it bring low; Many will it exalt;
When the earth shall be shaken to its depths,
And the mountains shall be crumbled to atoms,
Becoming dust scattered abroad,

And ye shall e sorted out into three classes.
Then there will be the Companions of the Right Hand; What will be the Companions of the Right Hand?
And the Companions of The Left Hand, - What will be the Companions of the Left Hand?
And those Foremost (in Faith) will be Foremost (in the Hereafter).
These will be Those Nearest to God;
In Garden of Bliss;
A number of people From those of old,
And a few from those of later times.
2. The Event Inevitable is the Hour of Judgment. People may doubt now whether it will come. But when it comes, as it will come, suddenly upon them, it will come with such tremendous reality that it will burnt deep into the experience of every soul. No one can then be deceived or entertain false notions about it.

There will be sorting out of Good and Evil, Or rather, there will be threemain classes. Among the Good there will be the specially exalted class, those nearest to God, and the Righteous people generally, called the Companions of the Right Hand (Ashab-ul-maimana). And there will be those in agony, the Companions of the Left Hand (Ashab-ul-mash-ama). Many who were high and mighty in this life will be brought low for their sins, and many who were lowly but virtuous will be exalted to various ranks and degrees. The old landmarks will be lost in the inner world, as they will be in the outer world.
Now, regarding the word “Foremost (in Faith)”, there are two meanings, and both are implied. (1) Those who have reached the highest degree in spiritual understanding, such as the great prophets and teachers of mankind, will also take precedence in the Hereafter. (2) Those who are the first I time-the quickest and readiest – to accept God’s Message – will have the first place in the Kingdom of Heaven. The category Foremost in Faith is nearest to God. And Nearness to God is the test of the highest Bliss.
3. There is a group of people called the sufis. Four interpretations are given for this name.

References:
The Holy Qur’an, Chapter 56 The Inevitable Event
Sirr al-asrar fi ma yahtaju ilayhi al-abrar - Abdulqadir Al-Jilani