Makhdoom Shaikh Sharufuddin al Maneri (Allah have mercy on him) said,
‘Spiritual masters have written about the veils in various books. They mention four; people; the world; Satan and the selfish soul (nafs).
People hinder our devotion to and worship of Allah. This world conceals the world to come. Satan downplays religion. One’s selfish soul acts as a veil with regards to The Lord.
Four veils can be enumerated but if you examine the matter, they all stem from one root, one’s selfish soul.
One gets overly preoccupied with people because of one’s selfish interest. Being immersed in worldly affairs also flows from self-interest. Agreeing to what Satan proposes also stems from selfishness.
Hence it is clear that selfish soul is the root of all these distortions. This is the origin of the adage, ‘The selfish soul is the greatest of all idols’.
In fine, whoever has brought his selfish soul to heel has been liberated from them all.’
Mine of Meaning, page 215