Solomon
Proverbs 11:9ESV·traditional attribution

With his mouth the godless man would destroy his neighbor, but by knowledge the righteous are delivered.

Matthew Henry Presbyterian @wholebiblehenry

Here is, 1. Hypocrisy designing ill. It is not only the murderer with his sword, but the hypocrite with his mouth, that destroys his neighbour, decoying him into sin, or into mischief, by the specious pretences of kindness and good-will. Death and life are in the power of the tongue, but no tongue more fatal than the flattering tongue. 2.

John Gill Reformed Baptist @doctorgill

An hypocrite with his mouth destroyeth his neighbour,.... Deceives him with his flatteries and lies, and draws him into destructive schemes and practices; or "corrupts" him, as the word (i) signifies, and as the Targum renders it, with false doctrines; so, with fair words and good speeches, such who lie in wait to deceive impose upon the simple and credulous; and false teachers, with their...

Jamieson-Fausset-Brown Reformed @jfbcommentary

(Compare Psa 35:16; Dan 11:32). The just is saved by superior discernment.