Proverbs 17:3

The fining pot [is] for silver, and the furnace for gold,.... Refiners of silver have their fining pots, in which they purify the silver from the dross; and goldsmiths have their crucibles to melt and purify their gold, by which assays of the worth and value of it may be made;but the Lord trieth the hearts; there is no vessel, as Gersom observes, in which they can be put and tried by creatures; a man does not know, nor can he thoroughly search and try his own heart, and much less the hearts of others; God only knows and tries them, Jer 17:9; The Septuagint, Vulgate Latin, and Arabic versions, render it by way of similitude, "as the fining pot is for silver", &c.