He that hideth hatred with lying lips, and he that uttereth a slander, is a fool.

Wesley's Notes

10:18 Lying lips - With flattering words. He here condemns two opposite vices, secret hatred, and manifest slander.

Jamieson-Fausset-Brown Bible Commentary

18. Both vices must one day be known and punished, and hence their folly.

Matthew Henry's Concise Commentary

10:7. Both the just and the wicked must die; but between their souls there is a vast difference. 8. The wise in heart puts his knowledge in practice. 9. Dissemblers, after all their shuffling, will be exposed. 10. Trick and artifice will be no excuse for iniquity. 11. The good man's mouth is always open to teach, comfort, and correct others. 12. Where there is hatred, every thing stirs up strife. By bearing with each other, peace and harmony are preserved. 13. Those that foolishly go on in wicked ways, prepare rods for themselves. 14. Whatever knowledge may be useful, we must lay it up, that it may not be to seek when we want it. The wise gain this wisdom by reading, by hearing the word, by meditation, by prayer, by faith in Christ, who is made of God unto us wisdom. 15. This refers to the common mistakes both of rich and poor, as to their outward condition. Rich people's wealth exposes them to many dangers; while a poor man may live comfortably, if he is content, keeps a good conscience, and lives by faith. 16. Perhaps a righteous man has no more than what he works hard for, but that labour tends to life. 17. The traveller that has missed his way, and cannot bear to be told of it, and to be shown the right way, must err still. 18. He is especially a fool who thinks to hide anything from God; and malice is no better. 19. Those that speak much, speak much amiss. He that checks himself is a wise man, and therein consults his own peace. 20,21. The tongue of the just is sincere, freed from the dross of guile and evil design. Pious discourse is spiritual food to the needy. Fools die for want of a heart, so the word is; for want of thought.