Jamieson, Fausset and Brown on Leviticus 25:17

17. Ye shall not oppress one another, but thou shalt fear thy God--This, which is the same as Le 25:14, related to the sale or purchase of possessions and the duty of paying an honest and equitable regard, on both sides, to the limited period during which the bargain could stand. The object of the legislator was, as far as possible, to maintain the original order of families, and an equality of condition among the people.