Leviticus 27:26–27 provide further details regarding the vows of persons and animals. According to the verses, the firstborn man or animal cannot be subject to a vow. This is because the firstborn already belongs to the Lord (see Exodus 13:2; Exodus 34:19–20).
26 Nul ne pourra sanctifier le premier-né de son bétail, lequel appartient déjà à l'Eternel en sa qualité de premier-né; soit veau, soit agneau, il appartient à l'Eternel.