Exodus 22:29

22:29 “Do not hold back offerings from your granaries or your vats. You must give me the firstborn of your sons.

Leviticus 27:10

27:10 He must not replace or exchange it, good for bad or bad for good, and if he does indeed exchange one animal for another animal, then both the original animal and its substitute will be holy.

Leviticus 27:28

Things Permanently Dedicated to the Lord

27:28 “‘Surely anything which a man permanently dedicates to the Lord from all that belongs to him, whether from people, animals, or his landed property, must be neither sold nor redeemed; anything permanently dedicated is most holy to the Lord.

Leviticus 27:33

27:33 The owner must not examine the animals to distinguish between good and bad, and he must not exchange it. If, however, he does exchange it, both the original animal and its substitute will be holy. It must not be redeemed.’”