Psalms 36:3

Iniquity - Sin; wickedness; evil.

The words of his mouth are iniquity - In the principle; and deceit calculated to pervert others, and lead them astray.

He hath left off to be wise, and to do good - His heart is become foolish, and his actions wicked. He has cut off the connection between himself and all righteousness.

The words of his mouth are iniquity and deceit - Are false and wicked. See the notes at Psalm 12:2. It is words do not fairly represent or express what is in his heart.

He hath left off to be wise - To act wisely; to do right.

And to do good - To act benevolently and kindly. This would seem to imply that there had been a change in his conduct, or that he was not what he once professed to be, and appeared to be. This language would be applicable to the change in the conduct of Saul toward David after he became envious and jealous of him 1 Samuel 18; and it is possible, as Amyraldus supposed, that this may have had particular reference to him. But such instances of a change, of feeling and conduct are not very uncommon in the world, and it may doubtless have happened that David experienced this more than once in his life.

36:3 Left off - Once he had some degrees of wisdom, but now he is become an open apostate.