Exodus Raba, 31:3

Another explanation of ‘If you lend money to any of My people’ (Exodus 22: 24). It is written, There is a grievous evil which I have seen under the sun, namely, riches kept by the owner thereof to his hurt; and those riches perish by evil adventure (Ecclesiastes. 5:12). Happy is the man who can withstand the test, for there is none whom G-d does not prove. He tries the rich man to see if his hand will be opened unto the poor, and the poor man He tries in order to see whether he will accept chastisement without repining, as it says, And that you bring the poor that are humbled to thy house (Isaiah. 58:7). If the rich man with stand his test and practice charity, then he will enjoy his wealth in this world, while the capital will be preserved for him in the Life to Come, and the Holy One, blessed be He, will, moreover, redeem him from the punishment of Gehinnom, as it says, Happy is he that considers the poor; the Lord will deliver him in the day of evil (Psalms 41:2). If the poor man withstands his test without rebelling he takes a double portion in the World to Come, as it says, For You do save the afflicted people (ibid, 18:28). Whence can you learn this?--From Job, who suffered in this world and whom G-d repaid in double measure, as it says, And the Lord gave Job twice as much as he had before (Job 42:10). The rich man, however, who grudges to give perishes with his wealth from this world, as it says, ’And those riches perish by evil adventure,’ for he is mean towards those who collect for charity. Why so? Because there is an ever rotating wheel in this world, and he who is rich to-day may not be so to-morrow, and also he who is poor to-day may not be so to-morrow. One He casts down, and the other He raises up, as it says, For G-d is judge; He puts down one, and lifts up another (Psalms 75:8). You will find that there are riches that positively harm their possessors and other riches that stand them in good stead. As an example of riches that do harm, take the case of Korah who was richer than all Israel and of whom it is written, So they, and all that appertained to them, went down alive into the pit (Numbers 16:33). Another example: Such was the wealth of the wicked Haman of whom it says, And Haman recounted unto them the glory of his riches (Esther 5:11), and of whom it is written, And that he and his sons should be hanged on the gallows (ibid 9:25). Riches that benefit their owners are like those of Jehoshaphat of whom it says, Now Jehoshaphat had riches and honour in abundance (II Chronicles, 18:1). What happened to him? -But Jehoshaphat cried out, and the Lord helped him (ibid, 31)...Thus there are ' Riches kept by the owner thereof to his hurt ‘. [Soncino Translation)