He plots trouble while on his bed; he sets himself in a way that is not good; he does not reject evil.
Psalm 36 Almost all interpreters agree in supposing, that in this psalm David in general expresses his wonder and amazement at the goodness of God, because, in the exercise of his favor and mercy, he bears with the wicked, who, notwithstanding, basely contemn him. The opinion which I have formed is somewhat different.
Commenting on Psalm 36:1-12
He deviseth mischief upon his bed. His place of rest becomes the place for plotting. His bed is a hot bed for poisonous weeds. God fearing men meditate upon God and his service; but when men turn all their thoughts and inventive faculties towards evil, their godlessness is proved to a demonstration. He hath the devil for his bed fellow who lies abed and schemes how to sin.
David, in the title of this psalm, is styled the servant of the Lord; why in this, and not in any other, except in Ps. 18 (title), no reason can be given; but so he was, not only as every good man is God's servant, but as a king, as a prophet, as one employed in serving the interests of God's kingdom among men more...
Commenting on Psalm 36:1-4