Leviticus 27:26

What belonged to the Lord by law could not be dedicated to Him by a vow, especially the first-born of clean cattle (cf. Exo 13:1-2). The first-born of unclean animals were to be redeemed according to the valuation of the priest, with the addition of a fifth; and if this was not done, it was to be sold at the estimated value. By this regulation the earlier law, which commanded that an ass should either be redeemed with a sheep or else be put to death (Exo 13:13; Exo 34:20), was modified in favour of the revenues of the sanctuary and its servants.

Here is, I. A caution given that no man should make such a jest of sanctifying things to the Lord as to sanctify any firstling to him, for that was his already by the law, Lev 27:26. Though the matter of a general vow be that which we were before obliged to, as of our sacramental covenant, yet a singular vow should be of that which we were not, in such circumstances and proportions, antecedently bound to. The law concerning the firstlings of unclean beasts (Lev 27:27) is the same with that before, Lev 27:11, Lev 27:12. II. Things or persons devoted are here distinguished from things or persons that were only sanctified. 1. Devoted things were most holy to the Lord, and could neither revert nor be alienated, Lev 27:28. They were of the same nature with those sacrifices which were called most holy, which none might touch but only the priests themselves. The difference between these and other sanctified things arose from the different expression of the vow. If a man dedicated any thing to God, binding himself with a solemn curse never to alienate it to any other purpose, then it was a thing devoted. 2. Devoted persons were to be put to death, Lev 27:29. Not that it was in the power of any parent or master thus to devote a child or a servant to death; but it must be meant of the public enemies of Israel, who, either by the appointment of God or by the sentence of the congregation, were devoted, as the seven nations with which they must make no league. The city of Jericho in particular was thus devoted, Jos 6:17. The inhabitants of Jabesh-Gilead were put to death for violating the curse pronounced upon those who came not up to Mizpeh, Jdg 21:9, Jdg 21:10. Some think it was for want of being rightly informed of the true intent and meaning of this law that Jephtha sacrificed h…

27:26 You may not dedicate: Every firstborn male, be it man or animal, already belonged to God (Exod 13:2; 34:19-20). Therefore, dedicating a firstborn was a useless exercise. The priest clearly had a use for the firstborn of animals fit for food or sacrifice (clean animals). The firstborn of a ceremonially unclean animal such as a donkey could be redeemed for 20 percent more than its value. Human firstborns had to be redeemed (Exod 13:11-13).