And thus shalt thou do unto them, to cleanse them: Sprinkle water of purifying upon them, and let them shave all their flesh, and let them wash their clothes, and so make themselves clean. Sprinkle water of purifying - מי חטאת mey chattath, water of sin, or water of the sin-offering. As this purifying water was made by the ashes of the red heifer, cedar-wood, hyssop, and scarlet; and the heifer herself was sacrificed, and her blood sprinkled seven times before the tabernacle, Numbers 19:3-6; she may be considered as a proper sacrifice for sin, and consequently the water thus prepared be termed the water of the sin-offering. As the ashes were kept ready at hand for purifying from all legal pollutions, the preparation might be considered as a concentration of the essential properties of the sin-offering, and might be resorted to at all times with comparatively little expense or trouble, and no loss of time. As there were so many things by which legal pollution might be contracted, it was necessary to have always at hand, in all their dwellings, a mode of purifying at once convenient and inexpensive.
As the water by which the Levites were here purified must have been the water prepared from the ashes of the red heifer, this ordinance was undoubtedly instituted before this time, though not described till Numbers 19:1-10 of this book; but that chapter might be in connection with any of the preceding ordinances, as well as where it is now found.
We see from Hebrews 9:13, Hebrews 9:14, that these ashes mingled with water, and sprinkled on the unclean, and which sanctified to the purification of the flesh, were intended to typify the blood of Christ, which purges the conscience from dead works to serve the living God, Hebrews 9:15; for as without this sprinkling with the water of the sin-offering the Levites were not fit to serve God in the wilderness, so without this sprinkling of the blood of Christ no conscience can be purged from dead works to serve the living God. See the notes on Numbers 19:1-10 (note).