Exodus 13:12

That thou shalt set apart unto the Lord all that openeth the matrix,.... Or "the womb", as in Exodus 13:2, and this phrase, "set apart", explains the word "sanctify" there, and shows that it signifies the separating of such to the use and service of God, causing it to "pass", as the word d here used signifies, from a man's own power and use, to be the Lord's only:

and every firstling that cometh from a beast which thou hast; or "even every firstling" e, explaining what is meant by what opens the matrix or womb, even every firstborn of a beast; though Jarchi interprets it of an abortion, what comes before its time, that this also should be set apart to the Lord; this must be understood of the firstlings of clean creatures, fit for food and sacrifice, such as the firstlings of cows, sheep, and goats, Numbers 18:17 as distinguished from unclean ones in the following verse:

the males [shall be] the Lord's; which explains what sort of firstborn of man and beast were to be set apart for his use, not females, though the first that opened the womb; but males.

d והעברת "et transire facies", Pagninus, Montanus, Fagius, Vatablus, Drusius, Cartwright; so Ainsworth. e וכל פטר "etiam quicunque vel quicquid aperuerit", Junius Tremellius, Piscator, Ainsworth.