The Gemara explains that Rav Sheshes needed to teach us the diyuk (inference) in the Mishna that bread which crusted is permitted. Rashi adds that this diyuk was not self-evident. However the Mishna seems to state clearly that the issur is merely if it won’t crust before Shabbos, which clearly implies that crusting is the benchmark. Why is this not self-evident?
The Gemara concludes that the Mishna begins with a discussion of Chazara, then proceeds to Shehiya, then concludes with a machlokes pertaining to Chazara – that Beis Shamai never allow Chazara altogether. Why does the Mishna interject with Shehiya rather than first concluding with the din of Chazara and then proceeding over to Shehiya?
The Mishna states that fuel of straw doesn’t present a concern since no coals are formed. If so how do we understand Bais Shamai who prohibit (shehiya of tavshil or chazara) even by ‘garuf’ (coals were shoveled) when there are no colas present?