Pesak: Some say that the Halachah does not follow Rav, since it says in Chulin (41a) that one may not slaughter into a cavity in Reshus ha'Rabim, lest one support (or act like) the heretics (who do so in order to throw the blood to idolatry). In the Chatzer it is permitted (for others do not see it).

Disclaimer: This is not a proof. In the Chatzer it is permitted, for even one who sees him says "he does so because he needs his Chatzer to be clean";

However, in other cases that one who sees will suspect [that he transgresses], it is forbidden even in inner rooms (where no one can see him).

Explanation (Rashi): This is a piece of wood. He will make a form on it.

Support: This resolves what people ask, that elsewhere (Bava Metzi'a 47b) it says "what is Asimon? It is Pulsa", and Rashi explained there that this is something without a form;

Question: Here it connotes that Pulsa has a form!

Answer: According to Rashi, this is fine. He will make a Pulsa without a form, and make a form on it.

Question: This is difficult for R. Tam, who explained that Asimon is of metal and it has a form, but (the form) is not important, and it is not accepted (like money);

If so, why do we discuss a Sela (coin)? Even an Asimon [should help]!

Answer: Perhaps specifically the form of a Sela is required.

Explanation #1 (Rashi): This is due to the mud, lest it be a Chatzitzah. They put mats under their feet.

Explanation #2 (R. Tam): They used to put mats vertically so everyone will not see them, and they will be ashamed from them, and [rush and] not immerse well.

Explanation #1: They are Pesulos to Kehunah Gedolah. She is not a full Besulah. Even though there was no Kohen Gadol in the days of Shmuel, he was stringent.

Explanation #2: Some say that [he forbade them] due to Zonah, and they are Pesulos even to a Kohen Hedyot.

Support (Yevamos 76a): The Halachah does not follow the son (Rabah bar Rav Huna), and not the father (Rav Huna, who disqualifies women who rub their genitals together from Kehunah);

And it says that even R. Elazar, who says that Bi'as Zenus makes a woman a Zonah... This connotes that [Rav Huna's] reason is due to Zonah.

Explanation #1 (Rashi): The Peras river testifies [in Bavel], for it flows down from Eretz Yisrael to Bavel, and it rises due to rain (in Eretz Yisrael).

Rebuttal: Bavel is east of Eretz Yisrael, and all rivers flow from east to west! (Rashash questions this, and points out that the Dano river flows from west to east. Perhaps Tosfos refers to the known rivers, of Gan Eden.)

Explanation #2 (R. Tam): They could recognize [in Bavel] that rain fell in Eretz Yisrael through the Peras backing up through its increase in Eretz Yisrael due to rain.

Explanation #1: Rainwater will be the majority over river water, i.e. Zochalin, and they are a Mikveh, and we say that a Mikveh is not Metaher through Zochalin, only through Ashboren (contained water);

A Mishnah (Mikva'os 5:5) teaches that Zochalin are like a spring, and Notfim (rainwater) is like a Mikveh;

A Beraisa in Toras Kohanim says "one might have thought that if he filled [Kelim] with water and carried it on his shoulder and made a Mikveh from the beginning, it is Tahor! [It answers] it says "Mayan" - just like a Mayan is bi'Ydei Shamayim, also a Mikveh is bi'Ydei Shamayim;

We ask that just like a Mayan is Metaher through Zochalin, we should say that a Mikveh is Metaher through Zochalin, i.e. even through Zochalin, and all the more so through Ashboren! It says "Ach Mayan" - a Mayan is Metaher through Zochalin, and a Mikveh is Metaher [only] through Ashboren. What is Ashboren? It is contained and endures.

Explanation #2: Some say that Shmuel's father did not want his daughters to immerse in [rivers] because they were Safek Zavos, and a Zav and Zavah require Mayim Chayim (running water). Perhaps rainwater will be the majority, and it is considered gathered.

Rebuttal #1: This is wrong. Firstly, why did he make Mikva'os for them? They require Mayim Chayim!

Rebuttal #2: The Tosefta (Zavim 3:1) says that a stringency of a Zav over a Zavah is that a Zav requires Mayim Chayim, and a Zavah does not require Mayim Chayim!

Question: According to Shmuel, we say that the only water (river) that is Metaher through Zochalin is the Peras in Tishrei, how can a Zav, who needs Mayim Chayim, immerse in Nisan?

Answer: He can immerse in a covered spring into which rainwater does not fall.

Question: Why are we concerned lest rainwater become the majority? We should say that every drop that falls in is Batel, like it says in Avodah Zarah (73a) that one who pours Yayin Nesech into a pit [of wine], even the entire day, it is all Kosher, for every bit that falls in is Batel!

Answer: "Every bit that falls in is Batel" does not help once the Isur is greater than the Shi'ur (i.e. here, the majority is rainwater);

In the case of Yayin Nesech, we say that "every bit that falls in is Batel" [only] before the Isur is enough to give taste to the Heter. (Bitul helps so that we do not forbid due to Mashehu of Yayin Nesech, like we forbid when Heter fell into it.)

Explanation: It is blessed from its Sela. The Targum of Sela is Kipei. I.e. it is blessed (increases) from its source, and not from rainwater.

Question: We say that [rivers] increase due to rain!

Answer: This is due to what it says in Ta'anis (25b) that for every drop [of rain] that descends from above, two drops ascend from the ground corresponding to it (the majority of the river's increase is due to water from the ground).

Pesak (R. Tam): The Halachah follows [this teaching of] Shmuel.

Source (R. Tam): This is proven from Bechoros (55b). A Beraisa says that R. Meir says that Peras is not the [real] name of the river, rather, it is Yuval. It is called Peras because its waters are Parin v'Rabim (increase);

This is not only regarding Peras. The same applies to all rivers. It mentioned Peras because it is greater than all rivers, and it is from Eretz Yisrael.

It says there that this supports Shmuel, who says that a river is blessed from its source. We rely on this to immerse in rivers, even if they increased greatly.

Explanation #1 (Rashi): An amputee whose foot was cut off makes the form of a foot and carves out a little to put the end of his leg in it. He does [not - some texts omit this] lean on it. Therefore, he may go out with his Kav, for it is his shoe;

R. Yosi forbids, for it is not an ornament, and it is not a shoe. It is a load.

Question (R. Tam): In Yoma (8b) it connotes that all agree that it is a shoe, and they forbid wearing it on Yom Kipur!

They argue about Shabbos. R. Yosi decrees lest it break, and he will come to carry it. R. Meir does not decree.

Answer: We can say that also here, they argue about this. R. Yosi holds that since it is not of leather, it does not fit snugly, there is concern lest it fall, and he will come to carry it.

Question: It says in the Gemara that if she did Chalitzah with a sandal... the Chalitzah is Kosher, and Shmuel said that this is like R. Meir;

Inference: According to R. Yosi, the Chalitzah is Pasul. What is the reason? It is a shoe!

Answer: Also this (Chalitzah) depends on this (the law of Shabbos). Since regarding Shabbos he decrees lest it break, it is not proper to walk in it. It is like a small person who did Chalitzah with a big person's shoe. It is Pasul, like it says in Yevamos (103b), because it says "Na'alo" - what is proper for him.

Question: How do they decree lest it fall and he will come to carry it? He has only one foot. (Without the Kav, his cut leg does not reach to the ground.) If it falls, he will not move from his place!

Answer (Ri): We discuss when he carries in his hand a staff, and primarily he walks [with his good leg,] supported by the staff. Now, even if it falls, he can walk.

Pesak: From here, if one's leg sinews shriveled, we can permit him to walk with his staff on Shabbos. (Since he cannot walk without it, it is like his shoe - Rosh Beitzah 3:5).

Explanation #2 (Rav Pores): An amputee has a support that he ties on his knees and it reaches to the ground. The shin is bent back, and at the end of the shin, in place of the foot, he makes a Kav to appear as if he has a foot.

They argue about the following. R. Yosi holds that since he does not support himself on [the Kav], rather, it hangs in the air, we are concerned lest it fall. R. Meir is not concerned.

Consequence: According to this, there is no proof to permit an amputee to go out with his staff.

Observation: We can permit from the Seifa of our Mishnah, which forbids only his Semuchos (leather that he puts under his knees), because his shins hang in the air, and perhaps it will fall, and he will come to carry it;

However, [the Mishnah] does not forbid the [small] benches in his hands. They are like a staff.

Question: According to this, why is Rava Metamei [the Kav] due to Midras? He does not lean on it!

Answer: Perhaps when he sits, sometimes he leans on it. Therefore, he makes a receptacle for tufts, lest he be damaged through the hardness of the wood when he sits.