As we’ve discussed earlier this week, the Rambam rules in Hilkhot Kelei Ha-mikdash (8:11) that a kohen may not wear his avneit (special belt) when he is not performing the avoda in the Beit Ha-mikdash. The avneit consisted of both wool and linen, and was thus generally forbidden to be worn due to the prohibition of sha’atnez. The Torah requires wearing the avneit while performing the avoda, essentially suspending the sha’atnez prohibition for this purpose, but at other times, it is forbidden for a kohen to wear the avneit due to the prohibition of sha’atnez.
The Mabit (Rav Moshe di Trani), in his Kiryat Sefer commentary to the Rambam’s Mishneh Torah, advances the surprising theory that the Rambam refers here to a rabbinic prohibition. On the level of Torah law, the Mabit claims, the Rambam concedes that a kohen is permitted to wear the avneit even when does not perform the avoda. The Mabit explains that clearly a kohen does not violate the prohibition of sha’atnez during those moments after he completes the avoda before he has an opportunity to remove the avneit. Once the Torah commands the kohen to wear the avneit while performing the avoda, it must, necessarily, also permit him to wear the avneit for a few minutes after performing the avoda, as a human being cannot possibly avoid wearing the avneit during those moments. It stands to reason, the Mabit contends, that just as the Torah does not forbid wearing the avneit during those moments, it permits wearing the avneit at any time when the kohen is in the Mikdash. And thus when the Rambam codifies a prohibition against wearing the avneit outside the framework of the avoda, he must necessarily refer to a prohibition enacted by Chazal as a safeguard against violations of sha’atnez.
Rav Asher Weiss (Minchat Asher, Parashat Pekudei, p. 460) noted the difficulty with the Mabit’s theory, as it seems to be contradicted by the Rambam’s formulation in Hilkhot Kilayim (10:32). There the Rambam writes explicitly that a kohen who wears the avneit when he does not perform the avoda, even if he is in the Beit Ha-mikdash, is liable to corporal punishment. This clearly indicates that the prohibition applies on the level of Torah law, as one is not liable to court-administered punishment for transgressing a prohibition enacted by Chazal.
In defense of the Mabit’s position, Rav Weiss suggests a distinction between a kohen who puts on the priestly garments when not performing the avoda, and a kohen who leaves his garments on after performing the avoda. Possibly, the Mabit speaks specifically of the latter case, when a kohen performed the avoda and did not then immediately remove the avneit. In such a case, according to the Mabit, the kohen does not violate the Torah prohibition of sha’atnez, which had been suspended for the purpose of the avoda and thus does not forbid wearing the avneit even after completing the service. In Hilkhot Kilayim, the Rambam addresses the situation of a kohen who puts on the avneit when he is not performing the avoda. In such a case, the sha’atnez prohibition was never suspended, and so the kohen violates the Torah prohibition of sha’atnez, even according to the Mabit.