The wicked shall be brought into those troubles which were either threatened by God or designed by wicked men against the righteous, and by that means, as by a ransom, the righteous shall be delivered. Thus Achan was a ransom for Israel, Joshua 7:26, and Haman for Mordecai.
Related Commentaries of Proverbs 21:18
Proverbs 21:18
18 The wicked shall be a ransom for the righteous, and the transgressor for the upright.