Matthew Henry Commentary Psalms 36:1-4

"The transgression of the wicked saith within my heart, There is no fear of God before his eyes. For he flattereth himself in his own eyes, That his iniquity will not be found out and be hated. The words of his mouth are iniquity and deceit: He hath ceased to be wise [and] to do good. He deviseth iniquity upon his bed; He setteth himself in a way that is not good; He abhorreth not evil." — Psalms 36:1-4 (ASV)

From this psalm, our hearts should be properly affected by hatred of sin and seek satisfaction in God's loving-kindness. Here is the root of bitterness from which all the wickedness of the wicked comes. It arises from contempt of God and the lack of proper regard for him. It also comes from the deceit they practice on their own souls.

Let us daily implore God to preserve us from self-flattery. Sin is very hurtful to the sinner himself, and therefore ought to be hateful; but it is not so. It is no wonder if those who deceive themselves seek to deceive all humankind; to whom will they be true, who are false to their own souls?

It is bad to do mischief, but worse to devise it, to do it with plot and management. If we willingly banish holy meditations in our solitary hours, Satan will soon occupy our minds with sinful imaginations. Hardened sinners stand by what they have done, as though they could justify it before God himself.