Albert Barnes Commentary Isaiah 31:7

"For in that day they shall cast away every man his idols of silver, and his idols of gold, which your own hands have made unto you for a sin." — Isaiah 31:7 (ASV)

For in that day - That is, in the invasion of Sennacherib, and the events that will follow from it.

Every man will cast away his idols - (see the note at Isaiah 30:22; compare the note at Isaiah 2:20).

For a sin - Or rather, the sin which your own hands have made. The sense is, that the making of those idols had been a sin, or sin itself. It had been the sin, preeminently, for which they were accountable.