'Purify Yourselves' in the Bible

“Tell the people: Purify yourselves in readiness for tomorrow, and you will eat meat because you cried before the Lord: ‘Who will feed us meat? We really had it good in Egypt.’ The Lord will give you meat and you will eat.

And encamp ye without the camp seven days: whosoever hath killed any person, and whosoever hath touched any slain, purify yourselves on the third day and on the seventh day, ye and your captives.

And as to every garment, and all that is made of skin, and all work of goats hair , and all things made of wood, ye shall purify yourselves.