Numbers 19:10-12

10And he that hath gathered the ashes of the heifer shall wash his clothes, and be unclean until the even. And it shall be unto the children of Israel, and unto the stranger that sojourneth among them, an everlasting statute.

11He that toucheth a dead person, any dead body of a man, shall be unclean seven days.

12He shall purify himself with it on the third day, and on the seventh day he shall be clean; but if he purify not himself the third day, then the seventh day he shall not be clean.