John Calvin Commentary Exodus 13:11

"And it shall be, when Jehovah shall bring thee into the land of the Canaanite, as he sware unto thee and to thy fathers, and shall give it thee," — Exodus 13:11 (ASV)

And it shall be when the Lord shall bring thee. He proceeds with what was touched upon in the beginning of the chapter regarding the consecration of the first-born, so that in this way they would bear witness to the special blessing of God who preserved them when He destroyed the first-born of the Egyptians.

But He commands the animals to³²⁹ be brought to Him, to be slain in the tabernacle. It is a common figure of speech to say that the faithful and their gifts were brought into God’s presence when they entered the tabernacle.

I understand that they were ordered, in Exodus 22:30, to keep the first-born for seven days to prevent deceptions. This was because if the young had been taken from their mothers' teats earlier and immediately delivered to the priests, the offering would have been useless. Yet I do not doubt that the eighth day was chosen because it was the one prescribed for circumcision.

An exception is added: a price was to be paid for a donkey, whose offering would have been unclean. Regarding their children, it was necessary that they should be redeemed, because they could not be offered in sacrifice, nor be made priests.

³²⁹ Observe A. V., “thou shalt set apart;” ., “thou shalt set apart;” margin, “cause to pass over;” , “cause to pass over;” Lat., “transferes.” “transferes.”