הלכה על שבועות 41:5

And if you will ask, "And why do we administer lashes for exchange - behold, it is a negative commandment that is rectifiable by a positive commandment, and that [commandment] is, 'and it and its exchange will be consecrated'"; the Sages, may their memory be blessed, have already given a reason for that matter. And they said (Temurah 4b) it is because there are two negative commandments about it, as I have written in this Order (Sefer HaChinukh 352); and a positive commandment does not come and uproot two negative commandments. And they also said another reason - since the negative commandment of exchange is not the same as the positive commandment about it: As if the community, or partners make an exchange, they do not create an exchange (it is not effective), even if they are warned not to exchange (it is forbidden). And since the negative commandment is not the same as the positive commandment, we do not say about it that its law is like a negative commandment that is rectifiable by a positive commandment. And if you will ask further, "And why do we administer lashes for this negative commandment, as it is possible to transgress it without an act, with speech alone - and the principle is established for us that we do not administer lashes for any negative commandment that does not have an act [involved] with it"; we have already written the answer in many places: That they, may their memory be blessed, explicitly excluded (Shevuot 21a) swearing, exchanging and cursing his fellow with [God's] name from this principle. As the Torah was very stringent about them to make them liable for lashes, even though there is no act [involved] with them.