The Mishna rules that the priestly gifts of the foreleg, cheeks, and abomasum (zeroa, lechayayim, v'keiva) apply both in the Land of Israel and abroad, during the Temple period and after its destruction, regarding non-sacred animals (chullin), but not consecrated animals (mukdashin). Although a logical inference (kal v'chomer) suggests consecrated animals should require gifts since they require the breast and thigh (chazeh v'shok), scripture excludes them by specifying that kohanim receive from consecrated animals only what is explicitly written in that context because of the limiting word "otam". The Mishna differentiates between two cases of animals with blemishes based on the underlying nature of their sanctity. In the first category, if a permanent blemish preceded consecration, the animal only attains monetary sanctity (kedushat damim); once redeemed, it remains obligated in priestly gifts and firstborn animal (bechora), and its shearing, work, offspring, and milk are permitted. In the second category, if consecration preceded the permanent blemish, the animal possesses intrinsic bodily sanctity (kedushat haguf). Even after redemption, the animal is exempt from priestly gifts and bechora, its shearing and work remain forbidden, and its offspring and milk are prohibited.

Analyzing the Mishna, the Gemara asks how one could have even thought that consecrated animals (kodshim) might be obligated in priestly gifts (matanot), given that non-sacred animals (chullin) initially seem to possess various unique severities. After addressing a slew of suggestions for stringency, they ultimately establish that no true element of stringency exists in chullin that does not also exist within the broader category of kodshim, it validates the need for a scriptural derivation. Conversely, the Gemara asks whether chullin should be obligated in the breast and thigh (chazeh v'shok) through a reverse kal v'chomer, since chullin possess the obligation of matanot which kodshim lack. Although the Gemara initially attempts to exclude chullin from chazeh v'shok using the word "zeh" in "v'zeh yihyeh mishpat hakohanim", it rejects this derivation and prefers to explain the reason for the exemption based on the fact that waving (tenufah) is practically impossible for chullin: performing it outside violates the requirement of "lifnei Hashem", while performing it inside violates the prohibition against bringing non-sacred items into the Temple courtyard (chullin ba'azara).

With "zeh" freed from excluding non sacred items from the law of chazeh v'shok, it is applied to Rav Chisda's ruling that one who damages or consumes priestly gifts prior to their distribution is exempt from financial restitution. The Gemara explains that this exemption is either derived directly from the word "zeh" in the verse, or an alternative reasoning is brought—that priestly gifts constitute property with no specific claimant (mamon she'ein lo tove'in).

The Gemara presents several challenges against the second explanation of Rav Chisda's exemption from restitution and some against Rav Chisda's exemption.

A braita rules that if one cuts an olive-bulk of flesh from a limb attached to a living animal, designating it for food only after cutting renders it pure, whereas designating it prior to cutting renders it susceptible to food impurity, as it touches the limb (which has high level impurity) as it is being cut. The Gemara presents Rav Asi's challenge to Rabbi Zeira as to why prior designation causes impurity, given that the cut site is a concealed place (tumat beit ha-satarim) and concealed impurity does not transmit impurity. Rava clarifies that the case involves a situation where liquids (hechsher) came upon it and Rabba bar Rav Chanan questions that, noting that it should not even require hechsher under the rule of an item destined to transmit severe impurity does not need hechsher, since here it came from a limb with a high level of impurity. Rava responds with a fundamental principle that when food functions as a connection or for a purpose other than food, it is considered "when used, it functioned like wood" and thus the rule of "destined to transmit severe impurity" does not apply. The Gemara presents five challenges that are resolved by applying this same explanation – "when used, it functioned like wood."

Returning to the Mishna dealing with a dangling limb and flesh on an animal, the Gemara asks for the rationale of Rabbi Shimon, who rules them pure in the case of the animal's death, challenging his view as completely illogical. The Gemara suggests that Rabbi Shimon disagrees with the reisha (opening clause) of the Mishna when the animal is still alive, based on Rabbi Yochanan's explanation that Rabbi Shimon derives from scripture "מכל אשר יאכל" that food is defined as such only if you can feed it to others; since a dangling limb or flesh from a living animal is forbidden to consume even for non-Jews, it cannot transmit food impurity. However, Rabbi Zeira raises a difficulty, explaining that if Rabbi Shimon disagrees with that case, it is because the flesh and limb are still somewhat attached, as learned from a Mishna in Uktzin (3:8). Thus, Rabbi Yochanan's explanation of Rabbi Shimon's view must apply to another case. The Gemara suggests it might apply to the metzi'ata (middle clause) where the animal was slaughtered, but this resolution is also difficult. In light of these difficulties, the Gemara returns to understand Rabbi Shimon's statement and Rabbi Yochanan's explanation, concluding that they actually refer to the seifa (final clause), not regarding the dangling limb (from which the difficulty was raised), but rather regarding the dangling flesh.

The Mishna discusses a dangling limb and flesh on a living human, ruling that they are pure during the person's lifetime. Upon the person's death, the flesh is pure from food impurity, while the dangling limb transmits impurity as a limb from a living person, but not as a limb from a corpse, according to Rabbi Meir. Rabbi Shimon considers it pure.

The Gemara again challenges Rabbi Shimon's view in the same manner as before. As a first resolution, it explains that Rabbi Shimon disagrees with a general underlying premise of Rabbi Meir's view. Subsequently, however, the Gemara successfully understands Rabbi Shimon's position in a different manner, based on a Mishna in Eduyot 6:3.

A braita discusses whether a sea-mouse transmits impurity—that is, whether the word "mouse" includes a sea-mouse. Within that discussion, it also addresses a mouse that is half flesh and half earth, deriving from scripture that it transmits impurity like a standard mouse. The braita concludes that a sea-mouse does not transmit impurity. The Gemara raises two challenges against the braita, but resolves both.

Following the discussion on the verse regarding the mouse, the Gemara turns to expound the words "ha-tzav le-minehu" from that same verse, which includes other unique creatures—the arod, ben nefilim), and the salamander—and notes Rabbi Akiva's marveling at the diversity of creation ("Mah rabu ma'asecha Hashem"). Another braita asserts that every creature found on land has a counterpart in the sea except for the chulda (weasel), derived from "kol yoshvei chaled". The Gemara digresses to an aggadic discussion regarding the questionable character of the inhabitants of Naresh (after mentioning a law regarding the beavers of Naresh), and presents an account where Rav Huna bar Torta witnessed a snake mating with a tzav to produce an arod, which Rava characterizes as a "miracle within a miracle" sent as a punishment.

The Mishna rules that a dangling limb or flesh attached to a live animal is susceptible to food impurity (tumat ochlin) in its place (if one thought to give it to a non-Jew to eat), provided a liquid came upon it rendering it susceptible to impurity, but it does not impart impurity as a limb from a living animal (ever min hachai).

If the animal is slaughtered, Rabbi Meir holds that the slaughtering blood creates susceptibility to food impurity, whereas Rabbi Shimon holds that it does not; neither holds that there is impurity of a limb from a live animal.

If the animal dies, Rabbi Meir holds that the flesh requires a liquid to render it susceptible to food impurity, while the dangling limb transmits impurity as a limb from a living animal, though not as a carcass (neveila). Rabbi Shimon, on the other hand, considers it pure from the impurity of a limb from a live animal.

Analyzing the Mishna, the Gemara asks why dangling flesh/limbs transmit food impurity but not impurity of a limb from a live animal, in the case where the animal is alive. It resolves that even if the flesh cannot heal (ein ma'alin arucha), impurity as a limb from a living animal requires the limb to completely detach from the verse "ki yipol". A braita supports this, ruling that even if attached by only a hair's breadth, it does not transmit impurity until it falls off, yet it remains susceptible to food impurity. The Gemara compares this to produce withered on the tree, such as dried figs, which transmit food impurity while still considered attached regarding the prohibition of picking on Shabbat.

Regarding the case in the Mishna where the animal was slaughtered, the Gemara asks what constitutes the core point of dispute between Rabbi Meir and Rabbi Shimon, ultimately offering six different explanations. Rabba explains that Rabbi Meir and Rabbi Shimon disagree on whether the main body of the animal acts as a "handle" (yad) to transmit hechsher to the dangling limb. Abaye and Rabbi Yochanan explain the debate differently: they disagree on the status of a handle where lifting the smaller dangling part does not carry the larger body (as it detaches), with Rabbi Meir considering it attached and Rabbi Shimon disagreeing.

The Gemara continues analyzing Rava's attempt to prove that "touch" (maga) can include tent-impurity (ohel) based on Rabbi Yosi's ruling regarding bed frames and window bars. Abaye rejects this proof, explaining that the case involves a space under a handbreadth (tefach), and due to a challenge raised against his explanation, Abaye is forced to explain that Rabbi Yosi holds concealed impurity does not break through (tumei tmunah eina boka'at). He proves his stance on concealed impurity from a Mishna discussing a cabinet (migdal) and Rabbi Yosi's commentary on it. A challenge is raised against Abaye from another case where Rabbi Yosi appears to hold that concealed impurity does break through and ascend (a dead dog that swallowed corpse flesh and is lying on a threshold). Rava resolves this by explaining that Rabbi Yosi does not rely on concealed impurity breaking out, but rather his dispute with Rabbi Meir regarding the dog is based on other considerations - whether the cavity of the dog contains a handbreadth of space and whether the threshold is considered part of the house.

The Gemara returns to clarify the identity of Rabbi Yosi's disputant, who holds that tent-impurity is not included in the term "touch." The Gemara identifies him as Rabbi Shimon, who disagrees with Rabbi Yosi in a braita by stating that there are three items that impart corpse-impurity through only two of the three standard modes (touch, carrying, and tent): a ladleful of dust of a human carcass (melo tarvad rakav) imparts impurity through carrying and tent, but not touch; a barley-grain-sized bone (etzem k'seorah) imparts impurity through touch and carrying, but not tent; and a tombstone lid and supporting frame (golel v'dofek) impart impurity through touch and tent, but not carrying. His ruling regarding dust demonstrates that he does not categorize tent-impurity under touch.

Regarding a carcass marrow-bone (kulit), the braita cites a scriptural source establishing that a sealed marrow-bone does not impart impurity, whereas a perforated one does. Rav Oshaya inquires whether a sealed marrow-bone that one intends to perforate is considered "lacking an action" (mechusar ma'aseh) because it requires perforation, or is it already considered perforated and can pass on impurity. He concludes that one's intent to perforate would make the bone susceptible to impurity.

The Mishna rules that a formed embryo egg of a creeping creature (sheretz) is pure unless perforated. Regarding a mouse that is half flesh and half earth, touching the flesh imparts impurity - and according to Rabbi Yehuda, touching earth directly opposite the flesh also imparts impurity. Analyzing the Mishna, the Gemara brings a braita deriving that a sheretz egg requires embryo formation (rikem) and a perforation as thin as a hairbreadth (k'chut ha-se'arah) to transmit impurity. Rabbi Yehoshua ben Levi clarifies that the half-earth mouse transmits impurity only if it developed flesh across its whole body. The braita discusses whether a sea-mouse is subject to the same laws of impurity as a land-mouse.

The Mishna distinguishes between the marrow-bones (kulit) of a corpse or consecrated sacrifices of pigul and notar (kodashim) and those of a carcass (neveila) or a creeping creature (sheretz). Touching a corpse or sacrificial marrow-bone imparts impurity whether sealed or perforated, whereas a neveila or sheretz marrow-bone imparts impurity through touch (maga) and carrying (masa) only if perforated.

The Gemara notes that the Mishna specifies that a corpse's marrow-bone imparts impurity through touch (maga), but omits tent-impurity (ohel), and analyzes why:

• Rav Yehuda son of Rabbi Chiyya concludes that there is less than an olive-bulk (kezayit) of marrow, and that interior marrow does not halakhically heal or complete the bone's exterior (mo'ach bifnim eino ma'aleh arucha mibachutz).
• Abaye maintains that interior marrow does heal the exterior, but interprets the Mishna as speaking of a bone scraped thin (sheshifah) along its circumference.
• Rabbi Yochanan holds that the Mishna's term "touch" (maga) actually includes tent-impurity (ohel). To resolve a difficulty, the Gemara explains that the marrow inside is loose and rattling (mitkashkesh); for a corpse, compressed impurity breaks through (boka'at v'olah), whereas for neveila, loose marrow requires a physical perforation to transmit impurity.

Two proofs are brought from Mishnayot in Ohalot in an attempt to demonstrate that the term maga can denote ohel, but difficulties are raised against both suggestions.

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).