Proverbs 27:21-23

Amplified Bible

²¹ 
The refining pot is for silver and the furnace for gold [to separate the impurities of the metal],
And each is tested by the praise given to him [and his response to it, whether humble or proud].
²² 
Even though you pound a [hardened, arrogant] fool [who rejects wisdom] in a mortar with a pestle like grain,
Yet his foolishness will not leave him.