Halakhah sur Les Nombres 21:2

And that is [the sense of that] which Scripture (Leviticus 27:29) states nearby, "Any dedication that is dedicated of a man you shall not redeem, he shall surely die"; as its content in the way of the simple meaning is that [in the case of] one who dedicates of a man that is not his - for example, those fighting against their enemies who make a vow, "If this nation is surely given into my hands, I will dedicate their cities" (Numbers 21:2) - [the objects of the vow] should die. As other nations are not included in the wellspring of blessings, as we have said; and [so] the expression of 'dedication' clings to them. And so did Ramban (Rambam) explain this verse in the way of its simple understanding (Ramban on Leviticus 27:29). And even though there are many midrashic explanations about this verse, there are seventy faces to the Torah and 'they are all straight for the one who understands.' And from this root they, may their memory be blessed, said (Arakhin 28a) that all that belongs to the Levites and the priests - whether land or whether movable items - cannot be dedicated. That is, even if the priest or the Levite said about his field that it be dedicated, it does not hold. As he is like one who dwells in his Master's house - the place of blessing and kindness and good - and all that he has is God's. And amidst blessing there is no place for 'dedication.'