On the Soul - Nafs 4

Restoring the Soul to a State of Rectitude

Thus, to train the soul and to restore it to a state of rectitude, and to advance it from the attribute of commanding [evil]** to the degree of tranquility*, is a great task. The perfection of human happiness lies in the refinement of the soul, and the completion of man's wretchedness lies in abandoning the soul to the demands of instinctual nature.

Hence God Almighty said, after invoking a multiple oath: {Truly he prospers who refines it, and he fails who corrupts it.} For the refinement and training of the soul yields knowledge of the soul, and knowledge of the soul leads to knowledge of God: ”He who knows his soul knows his Lord.” This knowledge is the summit of all felicity.

** see above, Sura 12-53

* Sura 89-27
{O Self, in complete rest and satisfaction!}
This highest stage of the soul is called the nafs al-mutma`inna (the soul at peace).

The Path of God’s Bondsmen; Najm al-Din Razi