Numbers 8:15
And after that shall the Levites go in to do the service of the tabernacle of the congregation: and thou shalt cleanse them, and offer them for an offering.
And after that shall the Levites go in,.... Not into the sanctuary, where only the priests entered, much less into the most holy place, where only the high priest went, and that but once a year, in neither of which places the Levites had anything to do, but into the court of the tabernacle:
to do the service of the tabernacle of the congregation: to watch there, and to assist the priests at the altar of burnt offering, to take down the tabernacle and bear the vessels of it, and set it up, as occasion required:
and thou shalt cleanse them, and offer them for an offering; cleanse them by sprinkling the water of purifying on them, and offer them by waving them as before; and indeed this is no new thing which is here observed, but what was already done, and therefore should be rendered, "when thou shalt have cleansed them", or "after thou hast cleansed them", &c. and so the particle "vau" is sometimes used {t}.
{t} See Noldius, p. 289, 290, 299.