The words of his mouth are iniquity and deceit: he has ceased to be wise, and to do good.
All Commentaries on Psalms 36:3 Go To Psalms 36
George Leo Haydock
AD 1849
Well, to those in distress, Psalm xl. 2. Though wise enough in worldly concerns, he seemed quite ignorant when any virtuous actions were proposed. (Calmet)
Sometimes ignorance is excusable when a person does his best to obtain knowledge. But when he is negligent, the ignorance is gross, and sinful in proportion to the importance of the thing. If one desire to be ignorant to prevent remorse, this only increases the guilt, and God often leaves such destitute of the ordinary graces which he gives to others; so that they fall into a reprobate sense, and into more horrible sins. (Worthington)