Numbers 19:9

19:9 “‘Then a man who is ceremonially clean must gather up the ashes of the red heifer and put them in a ceremonially clean place outside the camp. They must be kept ¹  for the community of the Israelites for use in the water of purification ²  – it is a purification for sin. ³ 

Numbers 19:18

19:18 Then a ceremonially clean person must take hyssop, dip it in the water, and sprinkle it on the tent, on all its furnishings, and on the people who were there, or on the one who touched a bone, or one killed, or one who died, or a grave.

[19:9]  ¹ tn Heb “it will be.”

[19:9]  ² tn The expression לְמֵי נִדָּה (lÿme niddah) is “for waters of impurity.” The genitive must designate the purpose of the waters – they are for cases of impurity, and so serve for cleansing or purifying, thus “water of purification.” The word “impurity” can also mean “abhorrent” because it refers to so many kinds of impurities. It is also called a purification offering; Milgrom notes that this is fitting because the sacrificial ritual involved transfers impurity from the purified to the purifier (pp. 62-72).

[19:9]  ³ sn The ashes were to be stored somewhere outside the camp to be used in a water portion for cleansing someone who was defiled. This is a ritual that was enacted in the wilderness; it is something of a restoring rite for people alienated from community.