Numbers 3:12

I have taken the Levites - instead of all the first-born - The Levites are taken for the service of the sanctuary in place of the first-born. The first-born were dedicated to God in commemoration of his slaying the first-born of the Egyptians, and preserving those of the Israelites. Even the cattle of the Levites were taken in place of the first-born of the cattle of the rest of the tribes. See Numbers 3:45. Several reasons have been assigned why God should give this honor to the tribe of Levi in preference to all the others, but they do not seem to me to be conclusive. Their zeal in destroying those who had corrupted the worship of God in the business of the golden calf, Exodus 32:28, has been thought a sufficient reason. A better reason is, that this was the smallest tribe, and they were quite enough for the service. To have had a more numerous tribe at this time would have been very inconvenient. Aaron, says Mr. Ainsworth, being in his priesthood a type of Christ, all these rites are fulfilled in him. For unto Christ God gave children, Hebrews 2:13. And they are a congregation of first-born, whose names are written in heaven, Hebrews 12:23, being of God's own will begotten by the word of truth, that they should be a kind of first-fruits of his creatures, James 1:18, to whom he also gives the first-fruits of his Spirit, Romans 8:23. These wait on and follow the Lamb, being first-fruits unto God and to the Lamb, Revelation 14:4; and Christ hath made us kings and priests unto God and his Father, that we may serve him day and night in his temple, Revelation 1:6; Revelation 7:15.

3:12 The first - born - Who were God's property, 13:12 , and to whom the administration of holy things was formerly committed, which now was taken away from them, either because they had forfeited this privilege by joining with the rest of their brethren in the idolatrous worship of the calf, or because they were to be mainly concerned in the distribution and management of the inheritances which now they were going to possess, and therefore could not be at leisure to attend upon the service of the sanctuary: and God would not commit it to some other persons in each tribe, which might be an occasion of idolatry, confusion, division, and contempt of sacred things, but to one distinct tribe, which might be entirely devoted to that service, and particularly to the tribe of Levi; partly out of his respect to Moses and Aaron, branches of this tribe; partly as a recompence of their zeal for God against idolaters, and partly because it was the smallest of the tribes, and therefore most likely to find both employment in, and maintenance for the work.