Matthew Poole and continuators on Leviticus 27:10

10 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.

Two words expressing the same thing more emphatically, q. d. He shall in no wise change it, neither for one of the same, nor of another, kind.

Partly because God would preserve the sanctity and reverence of consecrated things and therefore would not have them alienated, and partly to prevent abuses of them who on this pretence might exchange it for the worse, as reserving the judgement to himself.

(i. e.) both the thing first vowed and thing offered or given in exchange. This was inflicted upon him as a just penalty for his rashness and levity in such weighty matters.