It should be noted that there is no positive commandment that must be performed that is associated with temurah. Nevertheless, since the second animal becomes sanctified by means of the temurah Abayye puts it in the category of a lav ha-nitak la’asei.
In the first few dapim (=pages) of Massekhet Temurah, the Gemara has focused on questions regarding the punishment meted out to the individual who makes an animal temurah, that is, he tries to exchange a sanctified animal and transfer the holiness to another. On today’s daf Abayye points out that temurah should be considered a lav ha-nitak la’asei – a negative commandment that must be repaired by the performance of a positive commandment, which ordinarily does not entail any further punishment. (An example of a lav ha-nitak la’asei is the prohibition against stealing – see Vayikra 19:13 – that is followed by a positive commandment to return stolen property – Vayikra 5:23.)
Two reasons are often offered to explain the rule of lav ha-nitak la’asei. One approach suggests that performance of the positive commandment “corrects” the forbidden action, alleviating the need for any further punishment. Another approach posits that since the Torah associates a corrective action with the prohibition, it changes the nature of the prohibition so that it no longer matches the archetype lo tahsom shor be-disho – “Thou shalt not muzzle the ox when he treadeth out the corn” (Devarim 25:4) – and does not receive lashes.
The Gemara explains that temurah is unique inasmuch as it has two negative commandments and one positive commandment (“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 both it and that for which it is changed shall be holy” – see Vayikra 27:10), and therefore the punishment of lashes remains in force.