I am not sure who is the "Rashba" in the Nemukai Joseph. The Rashba from Spain? Or Rav Shimshon Ben Avraham? I had to correct my paragraph on Bava Metzia 110 because the NJ brings some idea from the Rashba that disagrees with the first part of our Tosphot there. But is that the same person who in the second part of Tosphot is disagreeing with the Ri? It occurred to me the NJ could very well be meaning the regular Rashba from Spain.

After writing this I decided it was the Rashba from Spain. --that seems clear from Bava Metzia in ch.s 6 and 7




 I might as well tell the general public what the issue is. It is חלב. That is there are certain parts of even a kosher animal that are forbidden These are the parts that would be offered in the Temple if it would be standing. They are the areas of fat that cover the stomach and that whole region. There is some verse about this somewhere in Leviticus I think but I don't know where it is off hand. This is a very serious issue and it involves כרת. That is when the Torah says "One who does such and such a thing will be cut off from his people." On every sin like that one has to bring a sin offering if it was done by accident. This issue is so serious that Reb Shmuel Berenbaum simply never ate meat at all. He would only eat chicken on Shabat.