Shabbos Daf 79 שבת דַף 79

Rav Nachman told Rava that unprocessed hide has the same minimum shiur to be liable for carrying, as processed hide, which is the amount to make a kameya. He brings a proof from a Mishnah later on that teaches that the minimum shiur for melaben (whitening wool), menapetz (disentangling it), and tzoveah (dying), is the same shiur for toveh (spinning the thread), since the raw wool stands to be spun into thread.

Here too, in the case of unprocessed hide, its shiur is the same shiur as tanned hide, since it stands to be tanned.

It was taught in a Baraisa regarding which parts of the tefillin renders one’s hands tamei when touched, in keeping with one of the eighteen enactments learned earlier on (Daf 14a).

It was taught in a Baraisa that it is Halachah L’Moshe M’Sinai that tefillin must be written on klaf, which is the outer layer of the hide, and a mezuzah must be written on duchsustus, which is the inner layer of the hide. When one writes on the klaf, he must write on the side of the klaf that originally faced the flesh of the animal, and when writing on duchsustus, he must write on the side that originally faced the hair of the animal.

This Baraisa was brought as one of the many challenges to Rav, who said that tefillin may also be written on duchsustus. The Gemara deflects this challenge by saying that the Halachah L’Moshe M’Sinai may be only stating how to fulfill the mitzvah of writing tefillin in the best way possible, however, tefillin written on duchsustus may still be kosher.