10 They must not exchange it or substitute a good one for a bad one, or a bad one for a good one; if they should substitute one animal for another, both it and the substitute become holy.

Read Leviticus 27:10 Using Other Translations

He shall not alter it, nor change it, a good for a bad, or a bad for a good: and if he shall at all change beast for beast, then it and the exchange thereof shall be holy.
He shall not exchange it or make a substitute for it, good for bad, or bad for good; and if he does in fact substitute one animal for another, then both it and the substitute shall be holy.
You may not exchange or substitute it for another animal—neither a good animal for a bad one nor a bad animal for a good one. But if you do exchange one animal for another, then both the original animal and its substitute will be considered holy.