And every firstling of an ass thou shalt redeem with a lamb,.... Which was given to the priest for it; and according to the Jewish canon , it might be redeemed with that only;"not with a calf, nor with an animal (a goat or a ram, as Bartenora interprets it), nor with a lamb slain, or torn to pieces.'
'Jarchi thinks the ass only was to be redeemed, and not the firstling of any other unclean creature, but his reasons are insufficient; all unclean creatures, as horses, camels, dogs, swine, &c. are included in it, as should seem from Nu 18:15 and this is the rather particularly mentioned, because there was a greater plenty of them than of horses and camels, and because they were very useful creatures; and if these were to be redeemed, then much more those of less value, and less useful.
Hence might arise the story and calumny, as some have thought, of the Jews worshipping an ass's head:and if thou wilt not redeem it, then thou shall break its neck; cut off its head on the back of the neck with a knife or cleaver, such as butchers use, as the Misnah , and its commentators, interpret it, so that the owner should have no profit by it:and all the firstborn of man amongst thy children shall thou redeem; with the price of five shekels of the sanctuary, and within thirty days of the birth of it, Nu 18:16 and these being to be redeemed as the unclean beasts were, shows that men are by nature unclean, and even the firstborn, whose names are written in heaven, the elect of God, and need redemption by the blood of the Lamb.
Misn. Becorot, sect. 1. sect. 5. lbid. sect. 7.