G-d instructs Moshe about the Shemita (Sabbatical year) for the land. For six years we may work the land, but in the seventh we must leave it to lie fallow. Anything that grows during this year may be eaten by anyone who wants it, or is left to the animals. We must also count a cycle of seven Sabbatical years and on the 50th year proclaim a Yovel (Jubilee year). This is also a year of rest for the fields and is a time when all slaves must be set free and all land returned to its original ancestral owners. The selling price of any land must reflect the fact that it will return to the original owners in the Jubilee year. G-d promises that in the sixth year the land will provide enough crops to last for Shemita and in the 48th year, also for the Yovel that follows. No land may be sold in perpetuity.
If a person becomes impoverished and is forced to sell their hereditary land, they or their relatives should redeem it as soon as they are able. The redemption price shall be calculated based on the sale price and the remaining years until the Yovel. Houses in walled cities may only be redeemed up until one year after they have been sold. If they are not redeemed by that time they shall become the permanent property of the purchaser. Houses in Levitical cities may always be redeemed, and if they are not redeemed they revert back to the Levites in the Jubilee year.
We are commanded to help our brethren who become impoverished with interest free loans. If a Jew becomes so impoverished that he is forced to sell himself as a slave, his master must not work him unnecessarily hard. The master must also provide food and accommodation for the slave's wife and children, and must set him free in the Jubilee year. Non-Jewish slaves however become hereditary property and should not be set free.
If a Jew is sold to a non-Jew as a slave he must be redeemed as soon as possible. We are obligated in all of these laws because G-d brought us out of bondage from the land of Egypt. We are commanded not to build idols or altars to false gods.