John Calvin Commentary Deuteronomy 28:43

"The sojourner that is in the midst of thee shall mount up above thee higher and higher; and thou shalt come down lower and lower." — Deuteronomy 28:43 (ASV)

The stranger that is within you shall get up above you. This also was a clear sign of God’s wrath, that the foreigners who lived in the land of Canaan on sufferance should, in a way, become its masters, for we know how those who are in debt are under the power of their creditors. In fact, what Solomon says is found to be true:

the rich ruleth over the poor, and the borrower is servant to the lender (Proverbs 22:7).

The Israelites, therefore, must have felt that God was opposed to them when they were dependent on their own guests, especially since He had promised that He would so enrich them that they should lend to others. This reversal of circumstances, then, clearly convinced them of their iniquities.

Meanwhile, it must be observed that poverty as well as wealth is in God’s hands. While wealth is a proof of God’s favor, poverty is counted among His curses. However, this occurs in such a way that God often disciplines His own children with need, or tests and exercises their patience without ceasing to be their Father, while He bestows abundance upon the reprobate, with which they may gorge themselves to their own destruction.

God’s blessing, however, shines forth in the elect, as far as it is beneficial for them; and it is not said in vain in the Psalm, Wealth and riches are in the house (of the just), in order that he may lend and be bountiful (Psalms 112:3).