Psalms 36:4

4.He meditates iniquity upon his bed Here the sacred writer shows that the wickedness of the ungodly man is of a secret and very determined character. It sometimes happens that many, who otherwise are not disposed to wickedness, err and fall into sin, because occasion presents itself all on a sudden; but David tells us, that the wicked, even when they are withdrawn from the sight of men, and in retirement, form schemes of mischief; and thus, although there is not presented before them any temptation, or the evil example of others to excite them to it, they, of their own accord, devise mischief, and urge themselves to it without being impelled by any thing else. Since he describes the reprobate by this distinguishing mark of character, that they devise mischief upon their beds, true believers should learn from this to exercise themselves when alone in meditations of a different nature, and to make their own life the subject of examination, so that they may exclude all evil thoughts from their minds. The Psalmist next refers to their stubbornness, declaring that they set themselves in a crooked and perverse way; that is to say, they purposely and wilfully harden themselves in doing evil. Finally, he adds the reason of their doing this: They abhor not evil Wilfully shutting their eyes, they rush forward in their headlong course till they spontaneously yield themselves the slaves of wickedness. Let us now shortly state the contrast between the ungodly and the people of God, contained in the preceding verses. The former deceive themselves by flattery; the latter exercise over themselves a strict control, and examine themselves with a rigid scrutiny: the former, throwing loose the reins, rush headlong into evil; the latter are restrained by the fear of God: the former cloak or disguise their offenses by sophistry, and turn light into darkness; the latter willingly acknowledge their guilt, and by a candid confession are brought to repentance: the former reject all sound judgment; the latter always desire to vindicate themselves by coming to the open light of day: the former upon their bed invent various ways of doing evil; the latter are sedulously on their guard that they may not devise or stir up within themselves any sinful desire: the former indulge a deep and fixed contempt of God; the latter willingly cherish a constant displeasure at their sins.