The Gemara has been discussing the laws of the bigdei kehuna – the priestly garments that served as the required uniform for kohanim who were performing the Temple service. One of the sources for the laws regarding these garments appears in Sefer Yeḥezkel, where the prophet Yeḥezkel – who, incidentally was a kohen – taught (44:18) that the priests are obligated to wear hats and pants made of linen, and that they cannot gird themselves ba-yaza. Abaye explains this term to mean that that their belts should not be tied around their bodies in a place where one sweats. A supporting baraita is brought where it is taught that the proper place on the body for tying a belt is where the elbows meet the body, neither above that nor below the waist.
According to Rashi, the place where the body sweats is any place where flesh rests against flesh, which limits the area of the chest above the elbows, as well as the area where the stomach doubles over the legs. Rav Hai Ga’on suggests that the simple meaning of the term ba-yaza refers to movement, and he understands the limits to be places on the body where the belt will move or fall from its place. This includes the chest, where it will naturally fall to the waist, and below the waist where it will fall to the legs. Yeḥezkel’s commandment is to secure the belt in a place where it will stay comfortably.
These teachings lead Rav Ashi to relate a story told to him by his contemporary, the Exilarch, Huna bar Natan. Once Huna bar Natan was visiting the Persian king, Izgadar, who noticed that Huna bar Natan’s belt was sitting on his waist higher than it should have. The king adjusted the belt and said: Your Torah says that you are a priestly nation and a holy people (see Shemot 19:6), i.e. he rebuked him gently for his fashion mishap. Upon relating this story to Ameimar, he invoked the words of the prophet Yeshayahu (49:23) that kings will raise and serve the Jewish people.
The Persian king mentioned in this story can be identified as Yazdegerd I who ruled from 399-420 CE. He was known as a peaceful king, and had good relations with Rome; he also showed great tolerance for other religions, Judaism and Christianity, a quality that led Persian religious leaders to brand him a sinner. As is clear in this story, he had great respect for Jews and for their leadership – according to some accounts he was married to the Exilarch’s daughter. It was during this period of tolerance that the Talmud Bavli began to be edited into its final form.