Proverbs 21:15

15 It is a joy to the just to do justice, And a terror for them that work iniquity. To act according to the law of rectitude is to these as unto death; injustice has become to them a second nature, so that their heart strives against rectitude of conduct; it also enters to little into their plan of life, and their economy, that they are afraid of ruining themselves thereby. So we believe, with Hitzig, Elster, Zckler, and Luther, this must be explained in accordance with our interpretation of Pro 10:29. Fleischer and others supplement the second parallel member from the first: וּפעל און מחתּה לפעלי אין; others render 15b as an independent sentence: ruin falls on those who act wickedly. But that ellipsis is hard and scarcely possible; but in general מחתה, as contrasted correlate to שׂמחה, can scarcely have the pure objective sense of ruin or destruction. It must mean a revolution in the heart. Right-doing is to the righteous a pleasure (cf. Pro 10:23); and for those who have און, and are devoid of moral worth, and thus simply immoral as to the aim and sphere of their conduct, right-doing is something which alarms them: when they act in conformity with what is right, they do so after an external impulse only against their will, as if it were death to them.

Note, 1. It is a pleasure and satisfaction to good men both to see justice administered by the government they live under, right taking place and iniquity suppressed, and also to practise it themselves, according as their sphere is. They no only do justice, but do it with pleasure, not only for fear of shame, but for love of virtue. 2. It is a terror to wicked men to see the laws put in execution against vice and profaneness. It is destruction to them; as it is also a vexation to them to be forced, either for the support of their credit or for fear of punishment, to do judgment themselves. Or, if we take it as we read it, the meaning is, There is true pleasure in the practice of religion, but certain destruction at the end of all vicious courses.

21:15 God is just, so he will reward the innocent and punish the wicked. No wonder the godly love justice while the wicked fear it.