Numbers 19:9

For the congregation of the children of Israel, i.e. for their use, and therefore in a fit place or places, whence any of them might easily procure it. For a water, or, to the water, i.e. to be put to the water, or mixed with it. Of separation, i.e. appointed for the cleansing of them that are in a state of separation, who for their uncleanness separated from the congregation. Either the heifer thus managed, or the water thus made and sprinkled, is a purification for sin, Heb. a sin, i.e. a kind of an offering for sin, or rather a mean for the expiation or cleansing of sin. The name of sin is sometimes given to the punishment of sin, and sometimes to the sacrifice or offering for sin.