ישעיהו מח:י פירוש: רש״י ואבן עזרא

but not as silver [lit. but not with silver.] Not with the fire of Gehinnom, as silver is refined through fire.

I have refined thee, by the exile.

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.