Numbers 8:7

Yahweh also said to Moses, “Go to the people and set them apart as holy today and tomorrow, and let them wash their garments;

“The one to be cleansed shall then wash his clothes and shave off all his hair and bathe in water and be clean. Now afterward, he may enter the camp, but he shall stay outside his tent for seven days.

“Bring the tribe of Levi near and have them stand before Aaron the priest, that they may minister to him.

The Levites, too, purified themselves from sin and washed their clothes; and Aaron presented them as a wave offering before Yahweh. Aaron also made atonement for them to cleanse them.

‘Now a man who is clean shall gather up the ashes of the heifer and deposit them outside the camp in a clean place, and the congregation of the sons of Israel shall keep it as water to remove impurity; it is purification from sin.