Leviticus 25:14-16

¹⁴And in the business of trading goods for money, do no wrong to one another.

¹⁵Let your exchange of goods with your neighbours have relation to the number of years after the year of Jubilee, and the number of times the earth has given her produce.

¹⁶If the number of years is great, the price will be increased, and if the number of years is small, the price will be less, for it is the produce of a certain number of years which the man is giving you.