17 "For every firstborn among the sons of Israel is Mine, among the men and among the animals ; on the day that I struck down all the firstborn in the land of Egypt I sanctified them for Myself. 18 "But I have taken the Levites instead of every firstborn among the sons of Israel . 19 " I have given the Levites as a gift to Aaron and to his sons from among the sons of Israel , to perform the service of the sons of Israel at the tent of meeting and to make atonement on behalf of the sons of Israel , so that there will be no plague among the sons of Israel by their coming near to the sanctuary ."

Matthew Henry's Commentary on Numbers 8:17-19

Commentary on Numbers 8:5-26

(Read Numbers 8:5-26)

Here we have directions for the solemn ordination of the Levites. All Israel must know that they took not this honour to themselves, but were called of God to it; nor was it enough that they were distinguished from others. All who are employed for God, must be dedicated to him, according to the employment. Christians must be baptized, ministers must be ordained; we must first give ourselves unto the Lord, and then our services. The Levites must be cleansed. They must be clean that bear the vessels of the Lord. Moses must sprinkle the water of purifying upon them. This signifies the application of the blood of Christ to our souls by faith, that we may be fit to serve the living God. God declares his acceptance of them. All who expect to share in the privileges of the tabernacle, must resolve to do the service of the tabernacle. As, on the one hand, none of God's creatures are his necessary servants, he needs not the service of any of them; so none are merely honorary servants, to do nothing. All whom God owns, he employs; angels themselves have their services.