John Gill's Exposition of the Whole Bible
Proverbs 13:17
A wicked messenger falleth into mischief,.... That does not do his errand right, nor deliver his message faithfully; such an one falls from the degree of honour in which he was into disgrace; he loses his master's favour that sent him; he is degraded from his post and office: he falls "by evil", or "into evil" r; by the evil of sin, into the evil of punishment. So wicked ministers and false teachers, such who transform themselves into the apostles of Christ and into angels of light, who corrupt the word of God, and handle it deceitfully; these shall receive their just condemnation; since they do a deal of mischief to the souls of men, and therefore shall fall into mischief themselves, even into everlasting perdition;
but a faithful ambassador [is] health; or, "an ambassador of truths" s; one that performs his embassy well and truly, he is salutary, useful, and profitable to himself, and to them that send him: the word for ambassador is translated an "hinge", Proverbs 26:14; and he is so called, because upon his negotiations abroad the hinge of political affairs turn at home. An ambassador of Christ, who does his work faithfully, keeps back nothing that is profitable, but declares the whole counsel of God; the sound doctrines he delivers are health to the souls of men; as well as he is approved of God and Christ; and so it turns to his own health and advantage, who will hear one day said unto him, "Well done, good and faithful servant", Matthew 25:23.
r ברע "in malum", V. L. Pagninus, Montanus, Tigurine version, Junius Tremellius, Pisccator, c. s ציר אמונים "legatus veritatum", Montanus, Vatablus.