'Purify Yourselves' in the Bible

Then Jacob said to his household and to all who [were] with him, "Get rid of the foreign gods that [are] in your midst and purify yourselves and change your garments.

And you, camp outside the camp seven days; all who killed a person and all who touched the slain purify yourselves on the third day and on the seventh day, you and your captives.

You will purify yourselves and every garment and every object of hide and all the work of goats' hair, and every object of wood."