They shall cast their silver, etc. The words remind us of Isaiah 2:20 and Isaiah 30:22, with the difference that here it is the silver and gold as such, and not the idols made of them, that are to be flung away.
They had made the actual metal their idol, and their confidence in it should be powerless to deliver them (Zephaniah 1:18). Their gold shall be removed; better, with the Revised Version, as an unclean thing.
The word implies the kind of impurity of Ezekiel 18:6; Ezekiel 22:10; Ezekiel 36:17; Isaiah 30:22. Instead of gloating, as they had done, over their money, men should shrink from it, as though its very touch brought pollution.
The Vulgate gives in sterquilinium, "to the dunghill." They shall not satisfy their souls. In the horrors of the siege, with everything at famine prices (2 Kings 6:25), and little or nothing to be had for them, their money would not stop the cravings of hunger.
It is characteristic that he applies to riches as such the very same epithet, stumbling block of their iniquity, as he had applied before (Ezekiel 3:20) to actual idolatry (comp. Colossians 3:5).