Numbers 19:10-12

Young's Literal Translation

¹⁰ and he who is gathering the ashes of the heifer hath washed his garments, and is unclean till the evening; and it hath been to the sons of Israel, and to the sojourner who is sojourning in their midst, for a statute age-during.

¹¹ `He who is coming against the dead body of any man -- is unclean seven days;

¹² he doth cleanse himself for it on the third day, and on the seventh day he is clean; and if he cleanse not himself on the third day, then on the seventh day he is not clean.