Proverbs 22:7

The rich rule over the poor, and the borrower is servant to the lender.

It's a sin to charge interest on a loan to a fellow believer:

Exodus 22:25 says, "If thou lend money to any of my people that is poor by thee, thou shalt not be to him as an usurer, neither shalt thou lay upon him usury."

Kate wrote: It's a sin to charge interest on a loan to a fellow believer:

Exodus 22:25 says, "If thou lend money to any of my people that is poor by thee, thou shalt not be to him as an usurer, neither shalt thou lay upon him usury."

Your point?

2 Kings 2:23-24 says:

"Then he went up from there to Bethel; and as he was going up the road, some youths came from the city and mocked him, and said to him, “Go up, you baldhead! Go up, you baldhead!” So he turned around and looked at them, and pronounced a curse on them in the name of the LORD. And two female bears came out of the woods and mauled forty-two of the youths." (NKJV)

Translation: Don't make fun of ball headed guys or the bears will get you.

Usury is in of itself a set limit that can be charged. It does not mean you can charge nothing.