Numbers 19:12-16

That one shall purify himself with the water on the third day and on the seventh day, and then he will be clean; but if he does not purify himself on the third day and on the seventh day, he will not be clean.

Anyone who touches a dead body, the body of a person who has died, and does not purify himself, defiles the tabernacle of the Lord; and that person shall be cut off from Israel. Since the water for impurity was not sprinkled on him, he will be unclean; his uncleanness is still on him.

‘This is the law when a person dies in a tent: everyone who comes into the tent and everyone who is in the tent will be unclean for seven days.

And every open container, which has no cover tied down on it, will be unclean.

Also, anyone who in the open field touches one who has been killed with a sword or one who has died naturally, or touches a human bone or a grave, will be unclean for seven days.