נחמיה, פרק י׳, פסוק ל״ז

The commitment to uphold the laws of the firstborn involves a clear distinction between different categories and how they are handled. The first group includes firstborn sons and the firstborn of impure animals. Because neither humans nor impure animals can be offered as sacrifices on the altar, they share a common requirement: they must be redeemed [רלב״ג]. The obligation is to provide a redemption payment rather than giving the firstborn itself [ביאור שטיינזלץ]. For a human firstborn, this payment is set at five shekels [מצודת דוד]. For an impure animal, such as a donkey, the redemption is made by giving a lamb [אבן עזרא, מצודת דוד, מלבי״ם]. Additionally, the redemption payment for this specific group does not need to be physically brought to the House of God [מלבי״ם].

A different process applies to pure animals, such as cattle and sheep. In contrast to humans and impure animals, the firstborn of pure animals must be physically brought to the House of God to be offered as sacrifices [אבן עזרא, מלבי״ם]. Whether through direct animal offerings or redemption payments, all of these gifts are ultimately directed to the priests. They are provided as compensation and a reward for the holy work the priests perform [מצודת דוד].