Generally speaking, as we learned in Massekhet Makkot, punishments meted out by Jewish courts were given only when the perpetrator committed an act forbidden by the Torah. If, however, the person neglected to perform a positive commandment, the Torah does not punish him in any way (although the Sages enacted punishments whose aim was to encourage performance of positive mitzvot). Similarly, negative commandments that do not involve forbidden actions – referred to in the Gemara as lav she-ein bo ma’aseh – are not punishable, since there was no forbidden action that was done.
Where does the law of temura fit in? Since trying to exchange a sanctified animal with another appears to involve speech but no action, is it considered to be a lav she-ein bo ma’aseh, or, perhaps, the act of speaking is considered significant?
On today’s daf Rabbi Yoḥanan is brought quoting Rabbi Yosei HaGelili as teaching that there are three exceptions to the rule of no punishment for a lav she-ein bo ma’aseh. The three exceptions are nishba (taking a false oath), meimar (announcing one’s intent to switch one consecrated animal for another – one who effects substitution) u’mekalel et ḥaveiro ba-shem (cursing one’s fellow while invoking the name of God).
In discussing our case – temura – the Gemara concludes that it really does not belong in this list. Rabbi Yoḥanan is quoted as telling the individual who brought the above teaching “Do not read: ‘And one who effects substitution’, because his very words constitute an action.” Since his words effect a real change of status in the second animal, which becomes consecrated, we view his speech as an action in this case.
Tosafot point out that there are other examples of speech for which punishment is given, e.g. eidim zomemin (witnesses that are found to be testifying falsely since they were not at the scene that they describe) or motzi shem ra (someone who falsely accuses his wife of premarital infidelity), and explain that in those cases the Torah itself clearly states the punishments associated with those statements.