'Purify Yourselves' in the Bible

Then Jacob said to his household, and to all who were with him, "Put away the foreign gods that are among you, purify yourselves, change your garments.

"Encamp outside of the camp seven days: whoever has killed any person, and whoever has touched any slain, purify yourselves on the third day and on the seventh day, you and your captives.

As to every garment, and all that is made of skin, and all work of goats' hair, and all things made of wood, you shall purify yourselves."