6, 7. Take the Levites . . . and cleanse them--This passage describes the consecration of the Levites. Although the tribe was to be devoted to the divine service, their hereditary descent alone was not a sufficient qualification for entering on the duties of the sacred office. They were to be set apart by a special ceremony, which, however, was much simpler than that appointed for the priests; neither washing nor anointing, nor investiture with official robes, was necessary. Their purification consisted, along with the offering of the requisite sacrifices (Le 1:4; 3:2; 4:4), in being sprinkled by water mixed with the ashes of a red heifer (Nu 19:9), and shaved all over, and their clothes washed--a combination of symbolical acts which was intended to remind them of the mortification of carnal and worldly desires, and the maintenance of that purity in heart and life which became the servants of God.

JFB.