Every firstling of an ass. The ass was the sole beast of burthen taken by the Israelites out of Egypt. (See Exodus 20:17.) Neither the horse nor the camel was among their possessions in the wilderness.
This is agreeable to the Egyptian monuments, by which the camel appears to have been rare in Egypt at this time, and the horse as yet mainly used for war and by the nobles in their chariots. With a lamb.
A lamb or a kid. The word used is the generic one. (See the comment on Exodus 12:3.) If thou wilt not redeem it, then thou shalt break its neck. This enactment was evidently made to prevent a refusal to redeem.
It would not require to be put in force, since by refusing under such a penalty a man would suffer pecuniary loss. All the first-born of men among thy children. Rather "among thy sons." Shalt thou redeem.
Later on, the amount of the redemption money was fixed at five shekels of the sanctuary for each. (Numbers 3:47.