Jas 5:3. "The rust (ios) of your riches shall be a witness against you" in the judgment, that your riches were of no profit, lying unemployed, and so contracting rust. Mt 6:19-20, "rust" (brosis), "corrosion."
Lay not up for yourselves treasures upon earth, where moth and rust corrupts, and where thieves break through and steal: but lay up for yourselves treasures in heaven, where neither moth nor rust doth corrupt, and where thieves do not break through nor steal:
your gold and silver is cankered, and their rust shall be a witness against you, and shall eat your flesh like fire: ye have been treasuring them up for these last days.