The Torah in Parashat Behukotai (Vayikra 27:10) forbids declaring the transfer of the sanctity of a consecrated animal onto another animal. This means that if an animal had been consecrated as a sacrifice, it is forbidden to proclaim that its sanctity should be transferred onto a different animal. If one did make such a proclamation, he has violated this prohibition, and both animals are now sacred and must be offered as sacrifices.
This prohibition – known as “Temura” – is unique in that it carries a punishment of Malkut despite the fact that no action is performed. Normally, one is not liable to Malkut for violating a “Lav She’en Bo Ma’aseh” – a Biblical prohibition which is transgressed without a physical act. In the case of Temura, however, one is liable to Malkut for violating this command even though it is violated through only a verbal pronouncement.
Additionally, one is liable to Malkut for violating this command even though it can be rectified through the performance of a Misvat Aseh. Normally, when the Torah presents a Misva to be performed following the transgression of a prohibition (“Lav Ha’nitak La’aseh”), the violator is not liable to Malkut for committing the violation, because it can be rectified by performing the Misva. Here, however, although the violation of Temura is rectified by treating both animals as sacred, nevertheless, one is liable to Malkut for transgressing the Temura prohibition. The reason is because the Torah issued two commands forbidding Temura, and the rule of “Lav Ha’nitak La’aseh” applies only in regard to a lone prohibition. If two prohibitions are violated, the associated Misvat Aseh rectifies only one, but not the other, and so the violator is still liable to Malkut.
This prohibition applies to both men and women, in all places, and at all times, even nowadays. Of course, in the absence of the Bet Ha’mikdash, one should not consecrate an animal. But if an animal was consecrated, it would be forbidden to declare the transfer of its sanctity onto a different animal.