Leviticus 27:31-33

New Catholic Bible

³¹ If someone wants to redeem his tithes, he shall add one-fifth to its value. ³² As to the tithes of the herd or the flock, of everything passing under the herdsman’s staff, the tenth to pass shall be holy to the Lord. ³³ He shall not investigate to see if it is good or bad, nor shall he exchange it for another. If he exchanges it, then the first animal and its substitute shall both be holy and are not to be redeemed.”