Numbers 19:12
“He 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.”
And he that gathereth 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, for a statute for ever.
He that toucheth the dead body of any man shall be unclean seven days.
He 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.
Whosoever toucheth the dead body of any man that is dead, and purifieth not himself, defileth the tabernacle of the Lord; and that soul shall be cut off from Israel: because the water of separation was not sprinkled upon him, he shall be unclean; his uncleanness is yet upon him.
This is the law, when a man dieth in a tent: all that come into the tent, and all that is in the tent, shall be unclean seven days.
Counter-Arguments
The strongest case that this verse does not belong in this theme.

Cross-References
“Jesus saith to him, He that is washed needeth not save to wash his feet, but is clean every whit: and ye are clean, but not all.”
“And ye shall not go out of the door of the tabernacle of the congregation in seven days, until the days of your consecration be at an end: for seven days shall he consecrate you.”
“Therefore shall ye abide at the door of the tabernacle of the congregation day and night seven days, and keep the charge of the Lord, that ye die not: for so I am commanded.”
“And the Levites were purified, and they washed their clothes; and Aaron offered them as an offering before the Lord; and Aaron made an atonement for them to cleanse them.”
“Purge me with hyssop, and I shall be clean: wash me, and I shall be whiter than snow.”