Charles Ellicott Commentary Proverbs 27:21

"The refining pot is for silver, and the furnace for gold; And a man is [tried] by his praise." — Proverbs 27:21 (ASV)

So is a man to his praise—that is, just as the fining-pot and furnace test the metals put into them, so too that on which a man prides or boasts himself tests him. Observe what this is—for example, wealth, outward display, popularity, or duty—and you will see what kind of man he is. Or it may mean that praise—that is, popularity—is as great a trial to a man as the fining-pot is for silver; he must be of good metal if he comes unhurt out of this. Or, again, it may signify: let a man test his praise—that is, examine by whom and for what he is praised, and be sure it is genuine and well deserved.