(45) And the cattle of the Levites instead of their cattle.—There appears to have been no numbering of the cattle. Had it been otherwise, an argument might have been used in support of the prospective reference of the command to number the firstborn, derived from the fact that it would have been impossible to ascertain the number of firstborn among the cattle. It appears, however, that the whole of the cattle of the Levites was given in redemption of the firstborn of all the cattle of the other tribes.

3:40-51 The number of the first-born, and that of the Levites, came near to each other. Known unto God are all his works beforehand; there is an exact proportion between them, and so it will appear, when they are compared together. The small number of first-born, over and above the number of the Levites, were to be redeemed, and the redemption-money given to Aaron. The church is called the church of the first-born, which is redeemed, not as they were, with silver and gold; but, being devoted by sin to the justice of God, is ransomed with the precious blood of the Son of God. All men are the Lord's by creation, and all true christians are his by redemption. Each should know his own post and duty; nor can any service required by such a Master be rightly accounted mean or hard.This redemption money (see the marginal references) would perhaps be exacted from the parents of the "youngest" children of the 22,273 Numbers 3:43. The cattle of the Levites was doubtless taken in the gross as an equivalent for the first-born cattle of the other tribes, which of course, no less than the first-born of men, belonged to the Lord; and in future would have to be redeemed Numbers 18:15; Deuteronomy 15:19. 41. the cattle of the Levites—These, which they kept to graze on the glebes and meadows in the suburbs of their cities, to supply their families with dairy produce and animal food, were also taken as an equivalent for all the firstlings of the cattle which the Israelites at that time possessed. In consequence of this exchange the firstlings were not brought then, as afterwards, to the altar and the priests. Take the Levites, to wit, the 22,000 reckoned up Numbers 3:39, See Poole "Numbers 3:39"

Take the Levites instead of all the firstborn among the children of Israel,.... The Lord had declared before that he had taken them, and now he bids Moses take them, who had numbered them, and give them to Aaron, instead of the firstborn, whose numbers were also taken for this purpose:

and the cattle of the Levites instead of their cattle; but not to be given to Aaron and his sons, or to the priests for their use, but to remain with the Levites for their use, who were now separated from the other tribes, and taken into the service of God; and as they were dedicated to God, so their cattle likewise for their support as his ministers:

and the Levites shall be mine; in a special manner his, being devoted to his service:

I am the Lord; who had a right to do this, and expected to be obeyed in it.

Take the Levites instead of all the firstborn among the children of Israel, and the cattle of the Levites instead of their cattle; and the Levites shall be mine: I am the LORD.