John Gill's Exposition of the Whole Bible
Proverbs 12:21
There shall no evil happen to the just,.... The evil of sin: no iniquity, as the Targum; which, and the Septuagint, Syriac, and Arabic versions, interpret of sin not being agreeable, convenient, suit able, and pleasing to a righteous man. Moreover, the Lord, by his Spirit and grace, weakens the power of sin in them; and, by his providence, prevents and removes occasion of sinning; and by his power preserves from it, from being overcome and carried away with it, at least finally and totally. Or the evil of punishment is here meant; no penal evil shall befall them; the punishment of their sin has been inflicted on Christ their surety, and therefore shall never be laid on them; and whatever afflictions may happen to them, which have the name and appearance of evil, these work together for their good, spiritual and eternal; so that, in reality, no evil thing, properly speaking, happens to them; see Psalms 91:10. Or whatever does come to them comes not by chance unto them, but by the decree and will of God, and is overruled for good;
but the wicked shall be filled with mischief; or "with evil" h, the evil of sin; with malice and wickedness, with all impiety and unrighteousness, with ignorance and error; with all kind of sins, both against the first and second table of the law, and so with all the consequences of sin: with the evil of punishment; with an evil conscience, with the terrors of it; with many distresses here, and with everlasting destruction hereafter. Some understand it of the mischief they devise to others, which they are full of and big with; and "though" they are, as Aben Ezra interprets the word, yet no evil shall happen to the righteous; the mischief contrived by them shall fall upon themselves.
h רע "malo", V. L. Pagninus, Montanus, Michaelis.