Solomon
Proverbs 10:18ESV·traditional attribution

The one who conceals hatred has lying lips, and whoever utters slander is a fool.

Matthew Henry Presbyterian @wholebiblehenry

Observe here, Malice is folly and wickedness. 1. It is so when it is concealed by flattery and dissimulation: He is a fool, though he may think himself a politician, that hides hatred with lying lips, lest, if it break out, he should be ashamed before men and should lose the opportunity of gratifying his malice.

John Gill Reformed Baptist @doctorgill

He that hideth hatred with lying lips,.... Or he whose "lying lips hide hatred", which is much the same; who pretends to be a friend, and outwardly behaves as one, but inwardly nourishes and cherishes hatred in his heart, which he covers and conceals, till he has a proper opportunity of showing it; as Absalom to Ammon, Joab to Amasa, the men of Anathoth to...

Jamieson-Fausset-Brown Reformed @jfbcommentary

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