Num Numbers, chapter Book of Numbers, chapter 19
And the tahor (clean person) shall sprinkle upon the tamei on the Yom HaShelishi, and on the seventh day; and on the seventh day he shall make himself tahor, and wash his clothes, and immerse himself in mayim, and shall be tahor at erev.19:19 On the messianic mikveh see Co 2:11-12