That thou shalt set apart unto the LORD all that openeth the matrix, and every firstling that cometh of a beast which thou hast; the males shall be the LORD's.

King James Translators' Notes

set...: Heb. cause to pass over

Jamieson-Fausset-Brown Bible Commentary

12, 13. every firstling, &c.-the injunction respecting the consecration of the first-born, as here repeated, with some additional circumstances. The firstlings of clean beasts, such as lambs, kids, and calves, if males, were to be devoted to God and employed in sacrifice. Those unclean beasts, as the ass's colt, being unfit for sacrifice, were to be redeemed (Nu 18:15).

Matthew Henry's Concise Commentary

13:11-16 The firstlings of beast not used in sacrifice, were to be changed for others so used, or they were to be destroyed. Our souls are forfeited to God's justice, and unless ransomed by the sacrifice of Christ, will certainly perish. These institutions would continually remind them of their duty, to love and serve the Lord. In like manner, baptism and the Lord's supper, if explained and attended to, would remind us, and give us occasion to remind one another of our profession and duty.

Matthew Henry's Whole Bible Commentary

Verses 11-16

Here we have,

I. Further directions concerning the dedicating of their firstborn to God. 1. The firstlings of their cattle were to be dedicated to God, as part of their possessions. Those of clean beasts-calves, lambs, and kids-if males, were to be sacrificed, Ex. 22:30; Num. 18:17, 18. Those of unclean beasts, as colts, were to be redeemed with a lamb, or knocked on the head. For whatsoever is unclean (as we all are by nature), if it be not redeemed, will be destroyed, v. 11, 13. 2. The firstborn of their children were to be redeemed, and by no means sacrificed, as the Gentiles sacrificed their children to Moloch. The price of the redemption of the firstborn was fixed by the law (Num. 18:16) at five sheckles. We were all obnoxious to the wrath and curse of God; by the blood of Christ we are redeemed, that we may be joined to the church of the firstborn. They were to redeem their children, as well as the firstlings of the unclean beasts, for our children are by nature polluted. Who can bring a clean thing out of an unclean?

II. Further directions concerning the catechising of their children, and all those of the rising generation, from time to time, in this matter. It is supposed that, when they saw all the firstlings thus devoted, they would ask the meaning of it, and their parents and teachers must tell them (v. 14-16) that God's special propriety in their firstborn, and all their firstlings, was founded in his special preservation of them from the sword of the destroying angel. Being thus delivered, they must serve him. Note, 1. Children should be directed and encouraged to ask their parents questions concerning the things of God, a practice which would be perhaps of all others the most profitable way of catechising; and parents must furnish themselves with useful knowledge, that they may be ready always to give an answer to their enquiries. If ever the knowledge of God cover the earth, as the waters do the sea, the fountains of family-instruction must first be broken up. 2. We should all be able to show cause for what we do in religion. As sacraments are sanctified by the word, so they must be explained and understood by it. God's service is reasonable, and it is then acceptable when we perform it intelligently, knowing what we do and why we do it. 3. It must be observed how often it is said in this chapter that by strength of hand (v. 3, 14, 16), with a strong hand (v. 9), the Lord brought them out of Egypt. The more opposition is given to the accomplishment of God's purposes the more is his power magnified therein. It is a strong hand that conquers hard hearts. Sometimes God is said to work deliverance not by might nor power (Zec. 4:6), not by such visible displays of his power as that recorded here. 4. Their posterity that should be born in Canaan are directed to say, The Lord brought us out of Egypt, v. 14, 16. Mercies to our fathers are mercies to us; we reap the benefit of them, and therefore must keep up a grateful remembrance of them. We stand upon the bottom of former deliverances, and were in the loins of our ancestors when they were delivered. Much more reason have we to say that in the death and resurrection of Jesus Christ we were redeemed.