1. Rav prohibited כחל because בקעה מצא וגדר בה גדר

When Rebbe Elazar ascended to Eretz Yisroel, he asked who had taught Rav that a roasted, untorn כחל is forbidden (following the second version of Rav’s ruling on the previous Daf). They indicated Rav Yitzchak bar Avudimi, but he said that he never taught Rav a Baraisa prohibiting כחל. Rather, בקעה מצא וגדר בה גדר – Rav “found an open field and built a fence around it”: (i.e., he discovered a city whose residents were completely unaware of the laws of בשר בחלב, so he prohibited even permitted cases of בשר בחלב, as a protective measure). For Rav once visited Tatlafush, and overheard a woman asking her friend how much milk is needed to cook a ליטרא of meat. Realizing they had never learned that בשר בחלב is prohibited, Rav remained there and prohibited even כחל for them. In another version, Rav Yitzchak bar Avudimi related that he had taught Rav a Baraisa that the כחל of a מניקה – nursing animal is prohibited, because it contains a large amount of milk. However, Rebbe Chiya taught this Baraisa without specifying that it referred to a nursing animal, assuming his students would understand this on their own. This led Rav to think that all כחל is prohibited.

1. One who goes to another place must follow the stringencies of both places

In סורא, they did not eat כחל at all (even if it was torn and roasted), but in פומבדיתא, they did eat כחל. Rami bar Tamrei of פומבדיתא once visited סורא on Erev Yom Kippur, and when everyone discarded the כחל of the animals they had shechted (following their custom), Rami bar Tamrei collected them and ate them. They brought him before Rav Chisda, who questioned his actions, and Rami explained that he was from the place of Rav Yehudah, who eats כחל. Rav Chisda objected that a Mishnah teaches that if one goes to another place with different customs, נותנין עליו חומרי המקום שיצא משם – we place upon him the stringencies of the place from which he left, וחומרי המקום שהלך לשם – and the stringencies of the place to which he has gone, so it was forbidden for him to eat כחל in פומבדיתא!? Rami bar Tamrei replied: חוץ לתחום אכלתינהו – I ate them outside the [city’s] boundaries, and was not beholden to its stringencies.

1. Beis Din does not force people to keep any מצות עשה whose reward is written nearby

Rav Chisda continued to question other actions of Rami bar Tamrei, and Rami defended all of them. Meanwhile, a man who was not honoring his father and mother was brought before Rav Chisda’s court. They tied him to a post to whip him, following the halachah that one who refuses to fulfill a positive commandment is whipped repeatedly, even until death. Rami bar Tamrei told them to release him, because a Baraisa states: כל מצות עשה שמתן שכרה בצדה – any positive commandment whose reward is written alongside it, אין בית דין שלמטה מוזהרין עליה – the lower (earthly) Beis Din is not warned about it (i.e., they are not required to force people to fulfill it). Since the Torah states that one who honors his parents merits long life, this implies that the punishment for failing to do so is the loss of long life, but no other punishment.