Allah says: "And [by] the Nafs and He who proportioned it And inspired it [with discernment of] its wickedness and its righteousness, He has succeeded who purifies it,

Allah says: "And [by] the Nafs and He who proportioned it And inspired
it [with discernment of] its wickedness and its righteousness, He has
succeeded who purifies it, And he has failed who instills it [with
corruption]."(Surah Ash Shams 91:7-10)
The Nafs invites the body to indulge in every form of material
activity. It is not concerned about moral principles or avoidance of
prohibited things. As long as the material body can find pleasure in a
thing or an action the nafs will entice the person to become involved.
If not checked it will cause the person to deviate from the correct
path.
It is because the nafs is attracted to materialistic matters that
Satan is able to influence a person. He does this by decorating
thematerial things to make them attractive and he is also able to
whisper inside the person material suggestions to impact upon his
thoughts. The results of the working of the nafs can make a
personentertain only material desires thereby becoming aslave of his
passion, desiresand ego. (12:53)
The nafs can also be cultured to act responsibly. This can be done by
restraining it from behaving like an animal and developing fear of
consequences.
The nafs can be controlled by the will of the person. This is a
special quality given by Allah, the power to choose what's right from
wrong.
Man can be influenced by knowledge and through acquisition of wisdom.
Knowledge will help a person to differentiate good from evil and right
from wrong; while wisdomwill enable its possessor to understand the
effect his action will have on the personality.
If the nafs is trained to become morally and spiritually good, it goes
through stages of growth. It moves away from being dominating to a
stage of self accusation. This stage is called Nafsul Lawwamah.(75:2)
In this stage the nafs is conscious of right and wrong. It
acknowledges its mistakes and tries to make amends by asking for
forgiveness and repenting.
The third station is called Nafsul Mutma'innah.(89 :27)In this stage
the nafs attains peace and tranquility. This is because it has
developed desires that do not conflict with the desires of Ruh (soul).
It does not impact negativelyon the ruh, rather, it helps to keep it
shining and its own energy becomes refined.
The mission of every person is to purify the nafs so that it can work
in harmony with the ruh, resulting in peace and stability.