Vayikra 27:33-34

Orthodox Jewish Bible

³³ He shall not search whether it be tov or rah, neither shall he change it; and if he substitute it at all, then both it and the substitute thereof shall be kodesh; it shall not be redeemed.

³⁴ These are the mitzvot, which Hashem commanded Moshe for the Bnei Yisroel in Mt. Sinai.