John Gill Commentary Psalms 36:4

"He deviseth iniquity upon his bed; He setteth himself in a way that is not good; He abhorreth not evil." — Psalms 36:4 (ASV)

He deviseth mischief upon his bed
He casts about in his mind on his pillow, when at leisure from all employment; and consults and contrives schemes how to compass his lusts, and to do injury to others, without doing which he cannot sleep;

he setteth himself in a way [that is] not good ,
in an evil way, which he chooses and delights in, and determines to continue in, he leaving the paths of righteousness to walk in the ways of darkness:

he abhorreth not evil ;
which is to be abhorred both because of its nature and effects; see (Romans 12:9) ; but on the contrary he loves it, takes pleasure in doing it, and in them that commit it: thus, by his thoughts, words, and actions, he appears to be devoid of the fear of God.