הִנֵּ֥ה צְרַפְתִּ֖יךָ וְלֹ֣א בְכָ֑סֶף בְּחַרְתִּ֖יךָ בְּכ֥וּר עֹֽנִי׃
Behold, I have refined thee, but not as silver; I have tried thee in the furnace of affliction.
Rashi on Isaiah
but not as silver [lit. but not with silver.] Not with the fire of Gehinnom, as silver is refined through fire.
Rashi on Isaiah
I have chosen for you Heb. בְּחַרְתִּיךָ. I have chosen for you the crucible of poverty as opposed to the crucible of fire. A crucible (כּוּר) is a vessel in which they melt silver and gold.