A SAFEK DOES NOT OVERRIDE SHABBOS
(Mishnah): We do not Mechalel Shabbos for a Safek or Androginus.
(Beraisa): "[Uva'Yom ha'Shmini Yimol Besar] Arlaso" - a Vadai overrides Shabbos, a Safek does not (this will be explained);
A Vadai [male] overrides Shabbos, Androginus does not;
R. Yehudah says, Androginus overrides Shabbos, he is Chayav Kares (if he grows up and does not circumcise himself);
A Vadai [eight day old] overrides Shabbos, a baby born Bein ha'Shemashos does not (we do not know which is his eighth day);
A Vadai overrides Shabbos, a baby born Mahul (without foreskin) does not:
Beis Shamai obligate Hatafas Dam Bris (drawing a drop of blood from the point on the Ever where circumcision would have taken place, but this does not override Shabbos);
Beis Hillel exempt.
R. Shimon ben Elazar says, all require Hatafas Dam Bris from a baby born Mahul, in case there is there is a foreskin there that is covered;
They argue about one who converted after he was already circumcised - Beis Shamai require Hatafas Dam Bris, Beis Hillel do not.
Question: The Beraisa says 'A Safek does not override Shabbos' - what does this mean?
Answer (Beraisa): We are Mechalel Shabbos for a baby born after seven months of pregnancy, not for an eight month baby (if its hair and nails are not properly developed, it is a Nefel);
If we are unsure if a baby is seven or eight months, we do not Mechalel Shabbos.
An eighth month baby [even if he appears to be alive, he is dead, he] is [Muktzeh] like a stone; one may not move him on Shabbos. However, his mother may bend over to let him nurse, on account of danger (if she is too full of milk; Rashi in Yevamos - also for danger to him).
HATAFAS DAM BRIS
(Rav): The Halachah follows the first Tana [regarding Hatafas Dam Bris];
(Shmuel): The Halachah follows R. Shimon ben Elazar.
Rav Ada bar Ahavah had a son born Mahul - he requested 13 Mohalim [to do Hatafas Dam Bris on Shabbos - all refused, so] he did so himself, and accidentally castrated him.
Rav Ada: I deserved to be punished for transgressing Rav's opinion!
Rav Nachman: You also transgressed Shmuel's opinion!
Shmuel holds that Hatafas Dam Bris is done on a weekday, but not on Shabbos!
Rav Ada holds that Shmuel obligates Hatafas Dam Bris even on Shabbos, for there is definitely covered foreskin:
(Rabah): [Shmuel holds that] there might be covered foreskin (therefore, it does not override Shabbos);
(Rav Yosef): [He holds that] there is definitely covered foreskin (therefore, it overrides Shabbos).
Support (Rav Yosef, for himself - Beraisa - R. Eliezer ha'Kapar): Beis Shamai and Beis Hillel do not argue about a baby born Mahul, all require Hatafas Dam Bris;
They argue about whether or not it overrides Shabbos - Beis Shamai say that it does, Beis Hillel say that it does not.
Inference: The first Tana [that R. Eliezer responds to; Tosfos - it is R. Shimon ben Elazar] holds that they do not argue about this, i.e. all agree that it overrides Shabbos!
Objection: Perhaps the first Tana holds that all agree that it does not override Shabbos!
Answer: This is unreasonable, for then R. Eliezer comes to teach about Beis Shamai, that they say it overrides Shabbos!
Objection: Perhaps he [primarily] comes to teach what Beis Shamai and Beis Hillel agree about (i.e. even Beis Hillel require Hatafas Dam Bris, unlike the first Tana)!
WHICH BABIES ARE CIRCUMCISED BEFORE THE EIGHTH DAY?
(R. Asi): Whenever the mother has Tum'as Yoledes, the baby is circumcised on the eighth day; whenever there is no Tum'as Leidah, he is not circumcised on day eight - "...V'Yoldah Zachar v'Tom'ah... uva'Yom ha'Shmini Yimol".
Question (Abaye): The Halachah before the Torah was given disproves this - there was no Tum'as Leidah, yet Milah was on day eight!
Answer (R. Asi): My rule applies from after Matan Torah.
Question: This is unlike Rav Huna and R. Chiya bar Aba:
(Rav Huna or R. Chiya bar Aba): We Mechalel Shabbos for [circumcision of] Yotzei Dofen (one born through Caesarian section) and a baby with two foreskins [one on top of the other; Me'iri - this cannot be, surely both must be cut, all would agree that we Mechalel Shabbos for this - rather, he has an extra Ever];
(The other of Rav Huna and R. Chiya bar Aba): We do not Mechalel Shabbos for them. (We do not Mechalel for a baby with two foreskins, perhaps Milah of only one of them overrides Shabbos, and we do not know which!)
[Regarding Yotzei Dofen] they argue only about Chilul Shabbos, but all agree that he is circumcised on day eight [even though there is no Tum'as Leidah]!
Answer: Indeed, their argument is about this - the latter opinion says that it does not override Shabbos because he is not circumcised on day eight!
Tana'im argue as R. Asi and Abaye argue (R. Chama is a Tana in the coming Beraisa):
(Beraisa): (It says "U'Ven Shemonas Yomim Yimol Lachem" - a slave is circumcised on day eight only if his master also had a full Kinyan (ha'Guf) in the mother.) Sometimes Yelid Bayis (a baby born to a Shifchah Kena'anis of a Yisrael) is circumcised on day one, sometimes he is circumcised on day eight; sometimes Miknas Kesef (a Nochri bought by a Yisrael to be an Eved Kena'ani) is circumcised on day one, sometimes he is circumcised on day eight.
If one bought a pregnant Shifchah and she gave birth afterwards, this is Miknas Kesef that is circumcised on day eight;
If one bought a Shifchah with her baby, this is Miknas Kesef that is circumcised on day one.
If one bought a Shifchah and she became pregnant afterwards, her son is Yelid Bayis that is circumcised on day eight;
R. Chama says, if she gave birth and then immersed [l'Shem Shifchus], her son is Yelid Bayis that is circumcised on day one; if she gave birth after immersing, her son is Yelid Bayis that is circumcised on day eight;
The first Tana holds that even if she gave birth first, and is not Teme'ah Leidah, he is circumcised on day eight.
Question: Indeed, according to R. Chama, Yelid Bayis is sometimes circumcised on day one, sometimes on day eight, and likewise regarding Miknas Kesef;
The Beraisa explained when Yelid Bayis is circumcised on day one and when on day eight (she gave birth before or after immersing, respectively);
If one bought a pregnant Shifchah, and she immersed and gave birth afterwards, this is Miknas Kesef circumcised on day eight;
If Reuven bought a pregnant Shifchah and Shimon bought her fetus, even if she gave birth after immersing, this is Miknas Kesef circumcised on day one.
But according to the first Tana, we find three of these - how do we find Yelid Bayis circumcised on day one?
Answer #1 (R. Yirmiyah): The case is, Reuven bought a Shifchah [solely] for her fetus.
Question: This is like the opinion that Kinyan Peiros (rights of usage) is unlike Kinyan ha'Guf;
But according to the opinion that Kinyan Peiros is like Kinyan ha'Guf, how can we answer?
Answer #2 (Rav Mesharshiya): The case is, he bought a Shifchah without intent to immerse her (the Mitzvos of slaves do not apply to her).