Solomon
Proverbs 15:4ESV·traditional attribution

A gentle tongue is a tree of life, but perverseness in it breaks the spirit.

Matthew Henry Presbyterian @wholebiblehenry

Note, 1. A good tongue is healing, healing to wounded consciences by comforting them, to sin-sick souls by convincing them, to peace and love when it is broken by accommodating differences, compromising matters in variance, and reconciling parties at variance; this is the healing of the tongue, which is a tree of life, the leaves of which have a sanative virtue, Rev 22:2.

John Gill Reformed Baptist @doctorgill

A wholesome tongue is a tree of life,.... A tongue that delivers out salutary instructions, wholesome advice and counsel; a "healing tongue" (w), as it may be rendered, which pacifies contending parties, and heals the divisions between them; to have the benefit of such a man's company and conversation is like being in paradise.

Jamieson-Fausset-Brown Reformed @jfbcommentary

A wholesome tongue--(Compare Margin), pacifying and soothing language. tree of life-- (Pro 3:18; Pro 11:30). perverseness therein--cross, ill-natured language. breach . . . spirit--(compare Isa 65:14, Hebrew), grieves, instead of appeasing.