'Defile' in the Bible

For I am Yahweh your God, so you must consecrate yourselves and be holy because I am holy. You must not defile yourselves by any swarming creature that crawls on the ground.

“Do not defile yourselves by any of these practices, for the nations I am driving out before you have defiled themselves by all these things.

If you defile the land, it will vomit you out as it has vomited out the nations that were before you.

You must keep My instruction to not do any of the detestable customs that were practiced before you, so that you do not defile yourselves by them; I am Yahweh your God.”

He is not to make himself unclean for those related to him by marriage and so defile himself.