Proverbs 12:20,21 - Joseph Benson’s Commentary on the Old and New Testaments

Deceit is in the heart of them that imagine evil Either, 1st, Deceit toward others, whom they design to deceive, and then to destroy, while good counsellors bring safety and joy to others: or, rather, 2d, To themselves. So the sense of the verse is, They whose hearts devise mischief against others, shall be deceived in their hopes, and bring that trouble upon themselves which they design against others: but they who, by good counsels, labour to promote the peace and happiness of others, shall reap the comfort and benefit of it themselves. There shall no evil happen to the just Either of sin or suffering, as the next clause explains this: no such evil shall befall them as commonly befalls the wicked, who are overwhelmed, or utterly destroyed by it; whereas good men are supported under their troubles, and shall be delivered out of them, and receive much benefit by them.