Numbers 19:16-18, 20-21

And whosoever in the open field toucheth one that is slain with a sword, or a dead body, or a bone of a man, or a grave, shall be unclean seven days. And for the unclean they shall take of the ashes of the burning of the sin-offering; and running water shall be put thereto in a vessel: and a clean person shall take hyssop, and dip it in the water, and sprinkle it upon the tent, and upon all the vessels, and upon the persons that were there, and upon him that touched the bone, or the slain, or the dead, or the grave

But the man that shall be unclean, and shall not purify himself, that soul shall be cut off from the midst of the assembly, because he hath defiled the sanctuary of Jehovah: the water for impurity hath not been sprinkled upon him; he is unclean. And it shall be a perpetual statute unto them: and he that sprinkleth the water for impurity shall wash his clothes, and he that toucheth the water for impurity shall be unclean until even.