As vinegar to the teeth,.... Which, with its coldness and sourness, blunts the teeth, and makes it troublesome to eat: the Septuagint, Syriac, and Arabic versions, render it, "as the sour grape is hurtful to the teeth;'' sets them on edge; and as smoke to the eye; dims the sight, causes the eye to water, and is very pernicious and vexatious: so is the sluggard to them that send him: that is, the slothful messenger, as the Targum explains it; who, being sent on an errand, is dilatory, does not make haste to bring back the answer; which is very vexatious to those that send him, raises their passions, makes them fretful and very angry, be it on what account it will: so slothful and unprofitable servants, to whom talents are given for usefulness, which they hide or use not, are very provoking to Christ, and whom he will order into outer darkness; those who have gifts for sacred service ought not to be slothful in business, but fervent in spirit, serving the Lord, Mat 25:26.