John Calvin Commentary Exodus 13:2

"Sanctify unto me all the first-born, whatsoever openeth the womb among the children of Israel, both of man and of beast: it is mine." — Exodus 13:2 (ASV)

Sanctify unto me all the first-born. This also refers to the First Commandment, because God asserts His right over the first-born, so that the recollection of their redemption would not be lost. For in this way the Israelites were admonished that they must honor that God by whose grace they had safely escaped from the common destruction of Egypt, and, moreover, that they were rescued by His special blessing, so that they would consecrate themselves to God their Deliverer. For the offering which He here requires was a mark of separation between them and the pagan nations.³²⁸

The first-born is called the opening of the womb because it is the beginning of generation. The expression, “among the children of Israel,” when applied to animals as well as to their own offspring and children, is meant to distinguish wild beasts from tame and domestic animals. But although He commands only the first-born of Abraham's descendants to be offered to Him, this principle must undoubtedly be extended to the sanctification of the whole people. For while He says that the first-born were His because they especially owed their preservation to His mercy, by the same reasoning He signifies that all were His own.

³²⁸ Omitted in Fr..