Or, “in the last days.” See on 2 Tim. 3:1. The statements of our Lord concerning the accumulation of riches (see on Matt. 6:24-34; Luke 12:13-34; etc.) reveal that the condition described in James 5:1-6 prevailed in NT times. The same is true of OT times (see Isa. 5:8; Amos 2:6-8; Micah 2:1-3; etc.). Greed has always led to oppression, and always will. But as with the violence and injustice of which Paul speaks in 2 Tim. 3:1-5 (see comment there; cf. James 5:7), greed and oppression are to reach a climax in the days immediately preceding the “coming of the Lord.” In the “last days” the wicked are certain to receive the reward that is stored up for them.

 By their selfish acts misers store up, as it were, a full measure of justice, which God will visit upon them in the day of judgment. The “rich” think to secure their future by an accumulation of material wealth, but in so doing, neglect at which would make them “rich toward God” (Luke 12:21). Each man, whether rich or poor, will be given what he deserves and has earned (see on Matt. 16:27; Luke 6:35; 1 Cor. 3:8; Rev. 22:11). The reward that the ungodly rich have stored up will be the “fire” of God’s wrath (see Rev. 20:15; 21:8).

It is possible to connect this phrase with the clause that follows, thus: “Since you treasured up fire in [or, “for”] the last days.” “Fire” would thus refer to God’s final judgment upon all the ungodly. “Rust” figuratively represents the worthless treasures that the wicked chose in preference to heavenly riches. That which has been mere “rust” will be consumed in the “fire” of the last day.

The fires of hell await all who set their hearts on acquiring material possessions.

 Accordingly, “the last days” (see below) would refer to the day of final judgment. Compare Rom. 2:5, which reads literally, “You are storing up wrath for yourself in the day of wrath.”

Or, “consume.” This “rust” involves the “destruction,” not only of material possessions but of body and soul as well.

 The tarnish on the gold and silver of the rich man’s wealth is evidence of disuse for a long period of time. Compare the experience of the man in the parable of the Talents who buried his one talent in the earth. (see on Matt. 25:25-30).

Or, “corroded.” James compares the best of worldly riches to worthless, rusted iron.

 This rust that marks unused possessions will be clear evidence against the “rich” in the day of judgment. Their money had been selfishly hoarded when it might have been used in service for God and man. The destruction of their treasures betokens their own impending doom. Men of OT times often laid up their money in a secret place they considered safe (see Isa. 45:3), for then there were no banks in which private funds might be deposited.