Numbers 19:11-16

‘The one who touches the dead body of any person shall be unclean for seven days. That one shall purify himself from uncleanness with the water [made with the ashes of the burned heifer] 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. Whoever touches a corpse, the body of anyone who has died, and does not purify himself, defiles the tabernacle of the LORD; and that person shall be cut off from Israel [that is, excluded from the atonement made for them]. Because the water for impurity was not sprinkled on him, he shall be unclean; his uncleanness is still on him. ‘This is the law when a man dies in a tent: everyone who comes into the tent and everyone who is in the tent shall be [ceremonially] unclean for seven days. Every open container [in the tent], which has no covering tied down on it, is unclean. Also, anyone in the open field who touches one who has been killed with a sword or who has died [of natural causes], or a human bone or a grave, shall be unclean for seven days.