Redeeming vows. This whole chapter deals with vows made to God.
So if I got cancer and prayed to God “heal me, and I’ll dedicate the rest of my life to serving you”, and then I was healed, but I didn’t want to actually quit my job and go into full time christian ministry, I could make a prescribed payment to the temple for the value of my life and the vow would be regarded as kept in God’s eyes.
The value calculation is functionally discriminatory, though its pragmatically reflecting a societal fact: the elderly and women have lower economic value to an agrarian society than a fit young male, so are worth less. There is also the gracious provision for financial hardship that runs through all of Leviticus.
This was pretty useful because in ancient Israel, the priesthood was not open to anyone not in the Levite tribe, and people often made vows.
Ditto if you ended up needing an animal that was dedicated to sacrifice, you paid the value of it plus 20% to the temple, and you kept the animal but were right with God.
Ditto promises of land, houses, etc.
They make it quite clear you can’t redeem what is God’s anyway: he owns the harvest tithes and the firstborn livestock. This is totally about voluntary additional tithes
These vows were very common in their culture – we are far more circumspect in my culture, though the passion and emotion these vows demonstrate in their relationship with God is confronting to my own relative coolness. And, we do often do we hear “over my dead body”! and similar things. I don’t know how many hats I am now due to eat. Its so accepted that our vows are meaningless they have just become just colourful figures of speech.
Its using economic sanctions to teach the people to be careful with their speech. Don’t promise bigger than you can deliver. Words matter.
Its also a nice element of practical non-perfectionism to end the book on. Its been all about God’s absolute inflexible standards. Here, there is a recognition of the ups and downs of passion and regret that humans experience. The old testament even often talks about God’s vows this way, like people can have him reconsider after he has burned with anger. Noah and Jonah bargain with God over his vows. Prayer is like this.
Its setting the stage for the big redemption of course. There is a way out. A debt owed to God can’t just be forgotten, but it can be paid for by another.