Rabbi Avahu cited in the name of Reish Lakish three situations where the measurement of walking four milin applies in halakha: traveling to find pure vessels for making dough, a minyan (or water for washing hands before prayer), and water for washing before eating bread. Rav Nachman bar Yitzchak corrects this statement on two counts: first, it was stated by Aivu, not Rabbi Avahu; second, it applied to four matters, not three, adding the case from the Mishna of walking on a leather mat for the time it takes to walk four milin, which removes its impurity. Rabbi Yosi b'Rabbi Chanina limits the requirement of walking four milin to the direction one is already traveling, noting that one is not required to travel even a single mil backward.

Regarding the impurity of human skin, a braita rules that a Roman legion entering a house renders the house ritually impure due to the presumption that soldiers carry skin from human skulls (karkaflein) for sorcery.

A Mishna outlines the rules of connection (chibbur) regarding ritual impurity when flaying an animal's hide, as the detached part functions as a handle (yad):

• If flayed for a mat - where one cuts along the length first and removes it from the sides - the hide remains connected to the flesh until one removes more than a grip's width (kedei achizah), which the Gemara defines as a doubled handbreadth.

• If flayed top to bottom for a flask, it remains connected until the chest is flayed.

• If flayed upside down from the legs (margil), the entire hide remains connected until fully removed, since the chest is reached only at the end.

• Regarding the neck hide, Rabbi Yochanan ben Nuri holds it is not connected, whereas the Sages hold it remains connected until completely flayed.

The Gemara asks what the status of the hide is once flayed beyond the grip's width for a carpet. Rav answers that the detached hide becomes pure, while the attached hide remains impure as a protector (shomer) of the meat. Rabbi Asi holds that the handbreadth adjacent to the meat that is detached remains impure. Three difficulties raised against Rabbi Asi's position are resolved.

A Mishna in Kelim (28:8) states that once the majority of an impure garment is torn, it becomes pure. Rabba bar Avuha limits this to a garment immersed that day (tevilat yom), as the owner's willingness to immerse it indicates he is unconcerned with ruining it and thus tore a full majority. Otherwise, one must be concerned that only half was torn, as the owner sought purity without destroying the garment and may not have been precise. Three difficulties raised against Rabbah bar Avuha's qualification - including one from our Mishna relying on precise measurements - are resolved in different manners.

Regarding the Mishna in Kelim, Reish Lakish and Rabbi Yochanan debate whether cut hide rebinds itself (chalim). Reish Lakish holds that hide rebinds itself, limiting the Mishna to cloth rather than leather, as torn leather rebinds and retains its impurity. Three difficulties raised against Reish Lakish, including two from our Mishna, are resolved.

Abaye explains that the dispute between Rabbi Yochanan ben Nuri and the Sages regarding neck hide centers on whether a protective covering destined to detach on its own (shomer he'asui linatek) retains the halakhic status of a protector (shomer).