Proverbs 27:19 (BSB)

As water reflects the face, so the heart reflects the true man.

From Proverbs 27. Also in the ESV.

Commentary on Proverbs 27:19

• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on Proverbs 27:19: This shows us that there is a way, 1. Of knowing ourselves. As the water is a looking-glass in which we may see our faces by reflection, so there are mirrors by which the heart of a man is discovered to a man, that is, to himself. Let a man examine his own conscience, his thoughts, affections, and intentions.
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Proverbs 27:19: As the fining pot for silver, and the furnace for gold,.... For the trying, proving, and purifying these metals; see Pro 17:3; so is a man to his praise; or "according to the mouth of his praise" (p); if his own mouth praises him, as in Pro 27:2;, he is known to be what he is, a foolish and vainglorious person: or "so a man...
• Jamieson-Fausset-Brown (Reformed), Commentary Critical and Explanatory on the Whole Bible on Proverbs 27:19: We may see our characters in the developed tempers of others.
• Geneva Bible Notes (Reformed), Geneva Bible Study Notes on Proverbs 27:19: As in water face [answereth] to face, so the heart of man to man. (h) There is no difference between men by nature, only the grace of God makes the difference.