Charles Ellicott Commentary Isaiah 48:10

"Behold, I have refined thee, but not as silver; I have chosen thee in the furnace of affliction." — Isaiah 48:10 (ASV)

I have refined you, but not with silver ... —The meaning is obscure, and perhaps depends on some unknown process in ancient metallurgy. Commonly the refining of silver is taken as a parable of God’s dealings with His people (Isaiah 1:25; Ezekiel 22:18–22; Malachi 3:3). Here the thought seems to be that the discipline had been less fierce than that of the refiner’s fire. Silver was purified seven times in the fire (Psalms 12:6); but that would have brought about the destruction of Israel, and He sought to spare them.

I have chosen you. —Better, I have tested you.