"40 And the Lord said to Moses, “List all the firstborn males of the people of Israel, from a month old and upward, taking the number of their names. 41 And you shall take the Levites for me—I am the Lord—instead of all the firstborn among the people of Israel, and the cattle of the Levites instead of all the firstborn among the cattle of the people of Israel.” 42 So Moses listed all the firstborn among the people of Israel, as the Lord commanded him. 43 And all the firstborn males, according to the number of names, from a month old and upward as listed were 22,273.
44 And the Lord spoke to Moses, saying, 45 “Take the Levites instead of all the firstborn among the people of Israel, and the cattle of the Levites instead of their cattle. The Levites shall be mine: I am the Lord. 46 And as the redemption price for the 273 of the firstborn of the people of Israel, over and above the number of the male Levites, 47 you shall take five shekels[c] per head; you shall take them according to the shekel of the sanctuary (the shekel of twenty gerahs), 48 and give the money to Aaron and his sons as the redemption price for those who are over.” 49 So Moses took the redemption money from those who were over and above those redeemed by the Levites. 50 From the firstborn of the people of Israel he took the money, 1,365 shekels, by the shekel of the sanctuary. 51 And Moses gave the redemption money to Aaron and his sons, according to the word of the Lord, as the Lord commanded Moses."
Numbers 3:40-51
These verses record the interesting transaction by which the Levites were substituted for the firstborn of Israel, and to which reference was made in an earlier Note. On the basis of a one for one exchange or substitution of Levites for firstborn, 273 firstborn remained unaccounted for. These, as has already been said, could not be simply left, but were to be re- deemed with silver, and the price paid in ransom for them to Aaron's sons. This foreshadows the idea of substitution as we find it in the New Testament doctrine of atonement, and it may underlie Peter's words in 1 Peter 1:18. The important thing in this transaction was the Lord's claim upon the firstborn, which was a symbol of His claim upon all the redeemed people. He had redeemed them all out of Egypt, so that they were all His, by right of redemption; but He claimed the firstborn for Himself as a symbol of this fact. This is analogous to the claim He made on the tithe, or tenth, of His people's goods and possessions, which was a symbol of the fact that everything they had was His, and that what they retained could not be regarded, as of right, their own. The firstborn (and by analogy the Levites) belonged to God by virtue of substitutionary atonement having been made for them in the Passover Lamb. They had been spared the visitation of death through the sheltering blood, the marks of which on the doors of Israel indicated that death had already knocked upon them. The Lord's claim upon them therefore is meant to signify that they really 'died' in the Passover judgment, so that they were 'not their own', but 'bought with a price'. It signified that, in this sense, they had no real right to be alive at all. Life for them was purely in the grace of God. This is the significance of the claim on the firstborn. In the New Testament this 'symbol' of belonging to the Lord comes into its own, and enlarges to the whole redeemed community. The body of believers is called 'the general assembly of the firstborn' (Hebrews 12:13), that is, every believer, incorporated into the body of Christ, is in the position of the firstborn, claimed by God, given to God, sealed unto Him, in being redeemed by the precious blood of Christ. We are no longer our own, but the Lord's, a holy priesthood offering up spiritual sacrifices acceptable to God by Jesus Christ (1 Peter 2:5; cf also 2 Corinthians 5:14,15).