12 you are to give over to the Lord the first offspring of every womb. All the firstborn males of your livestock belong to the Lord.
12 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.
12 you shall set apart to the Lord all that first opens the womb. All the firstborn of your animals that are males shall be the Lord's.
12 you are to set aside the first birth out of every womb to God. Every first birth from your livestock belongs to God.
12 that you shall set apart to the Lord all that open the womb, that is, every firstborn that comes from an animal which you have; the males shall be the Lord's.
12 you must present all firstborn sons and firstborn male animals to the Lord, for they belong to him.
Matthew Henry's Commentary on Exodus 13:12
Commentary on Exodus 13:11-16
(Read Exodus 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.