James 5:3

Your gold and silver is cankered Literally, rusted, the word being used generically of the tarnish that sooner or later comes over all metals that are exposed to the action of the air.

shall be a witness against you Better, for a witness to you. The doom that falls on the earthly possessions of the ungodly shall be, as it were, the token of what will fall on them, unless they avert it by repentance.

shall eat your flesh as it were fire The last words have been sometimes taken as belonging to the next clause, "as fire ye laid up treasure," but the structure of the English text is preferable. The underlying image suggested is that the rust or canker spreads from the riches to the very life itself, and that when they fail, and leave behind them only the sense of wasted opportunities and the memories of evil pleasures, the soul will shudder at their work as the flesh shudders at the touch of fire. We may perhaps trace a reminiscence of the "unquenchable fire" devouring the carcases in Gehenna, as in Mark 9:44.

Ye have heaped treasure together for the last days Better, Ye laid (or, ye have laid) up treasure in the last days. The preposition cannot possibly have the sense of "for." St James shared the belief of other New Testament writers that they were living in "the last days" of the world's history, and that the "coming of the Lord" was nigh (1 John 2:18; 1 Corinthians 15:51; 1 Thessalonians 4:15). For those to whom he wrote the words had a very real truth. They were actually living in the "last days" of the polity of Israel. In the chaos and desolation of its fall their heaped-up treasures would avail but little. They would be marked out in proportion to their wealth, as the first to be attacked and plundered.