The Lord speaks to Moses: Israel must not do what was done in Egypt, where they had lived, nor what will be done in Canaan, where he is leading them. They are to keep his decrees and walk in them, for whoever keeps them will live by them. The reason is repeated: I am the Lord.
A list of forbidden relations within the family follows: with a mother, a stepmother, a sister, a granddaughter, an aunt, a daughter-in-law, a sister-in-law and other close relatives. Also forbidden are relations with a woman during her menstrual uncleanness, with a neighbor's wife, and giving a child to be passed through fire to Molech, which profanes the name of the Lord. Sexual relations between men and with animals are forbidden, called an abomination and a perversion.
The Lord warns that the peoples Israel will drive out defiled themselves with these practices, and so the land itself became defiled and vomited them out. If Israel does them, the land will vomit them out too. Whoever commits them will be cut off from his people. The chapter ends with the command to keep what the Lord orders and not to defile themselves with those customs.