Leviticus 18:3, 24, 30

After the doings of the land of Egypt, wherein ye dwelt, shall ye not do: and after the doings of the land of Canaan, whither I bring you, shall ye not do: neither shall ye walk in their ordinances.

Defile not ye yourselves in any of these things: for in all these the nations are defiled which I cast out before you

Therefore shall ye keep mine ordinance, that ye commit not any one of these abominable customs, which were committed before you, and that ye defile not yourselves therein: I am the LORD your God.