1) THE REQUIREMENT OF MILAH AND TEVILAH FOR A CONVERT
QUESTION: The Mishnah (70a) teaches that an Arel may not eat Terumah. Rebbi Elazar says that this Halachah is derived from the words "Toshav v'Sachir," which describe who may eat Terumah (Vayikra 22:10) and who may eat the Korban Pesach (Shemos 12:45): Just as an Arel may not eat the Korban Pesach (Shemos 12:48), so, too, an Arel may not eat Terumah.
Rebbi Akiva derives this Halachah from a different source -- from the extra words in the verse, "Ish Ish" (Vayikra 22:4).
The Gemara inquires what the words "Toshav v'Sachir" teach according to Rebbi Akiva. Those words cannot teach that a circumcised Nochri may not partake of the Korban Pesach, because as long as he is a Nochri his circumcision does not remove him from the status of an Arel. Rather, those words teach that a convert who performed Milah but did not yet perform Tevilah may not partake of the Korban Pesach, and that a "Katan she'Nolad Mal" -- a child born circumcised -- may not partake of the Korban Pesach (Hatafas Dam Bris must be done to him before he may partake of the Korban).
Why does Rebbi Akiva need "Toshav v'Sachir" to teach that a convert who performed Milah but not Tevilah may not partake of the Korban Pesach? The Gemara earlier (46a-b) teaches that a convert's conversion process is not valid until he performs both Milah and Tevilah. The source for this law is the Torah's description of the conversion of the Jews when they left Mitzrayim, who performed both Milah and Tevilah before they received the Torah at Sinai. Rebbi Akiva also should learn the requirement for Milah and Tevilah from there. Accordingly, before the convert performs Milah and Tevilah he still has the status of a Nochri and, consequently, an Arel. As an Arel, he may not partake of the Korban Pesach. Why does Rebbi Akiva need a special source for this law?
ANSWERS:
(a) TOSFOS (46b, DH Ki Pligi) explains that although Rebbi Akiva agrees with the Chachamim (46a) that both Milah and Tevilah are necessary for conversion, he disagrees with the source for that requirement and derives it from the verse cited here, and not from the conduct of the Jewish people when they left Mitzrayim.
(b) The RITVA and TOSFOS YESHANIM (46b, DH Od Piresh and DH Divrei Rebbi Yehoshua) explain that although a Nochri who is circumcised is considered an Arel under most circumstances, if he performed circumcision for the specific purpose of becoming a convert he is not considered an Arel.
The Ritva may be consistent with his opinion expressed earlier (see Insights to Yevamos 47:2:c), that the Milah prior to conversion serves to remove the Tum'ah of the Nochri. Only when his Tum'ah is removed can his Tevilah be effective. The Tevilah, in contrast, serves to sanctify the convert with the Kedushah of Yisrael. Once the Milah of Gerus has removed the Tum'ah of the Nochri, he no longer can be called an Arel like other Nochrim.
(c) The RASHBA adds that not only is a convert who performed Milah but not Tevilah no longer considered an Arel, he is considered a partial Jew, and thus he is not in the category of Arel like other Nochrim. It is not because the Milah removes his status of Arel, but because the Milah makes him a partial Jew. Since he is considered a partial Jew, the status of Arel is removed.
The Rashba also seems to be consistent with his own opinion as expressed earlier (ibid.), where he explains that Milah is the beginning of the Gerus process and is not merely a preliminary act to the Gerus process. Tevilah, therefore, is compared to the "Gemar Din" and not the "Techilas Din." (See Insights to Yevamos 47:2:c.)

71b----------------------------------------71b

2) A WOMAN'S OBLIGATION TO PERFORM MILAH FOR HER SON
QUESTION: The Beraisa discusses the law that a person's son (or servant) must be circumcised in order to partake of the Korban Pesach, as the Torah says (Shemos 12:44, 48). The Beraisa states that if the son is not circumcised at the time of the Shechitah of the Korban Pesach, the father may not slaughter it on his behalf, and if the son is not circumcised at the time of the eating of the Korban Pesach, the father may not eat it.
The Gemara asks how it is possible to have a situation in which one is permitted to perform the Shechitah of the Korban Pesach (when one has no uncircumcised son) and yet not be able to eat the Korban Pesach a few hours later (when one has an uncircumcised son). It cannot be that the son was born between the time of the Shechitah and the Achilah, because the Torah says only that an uncircumcised son to whom it is possible to do Milah prevents his father from eating the Korban Pesach, but it is not possible to circumcise a son less than eight days old. Rava answers that the Beraisa refers to a case in which "his father and his mother were incarcerated" during the time of Shechitah but were freed at the time of Achilah. Since it was not possible for them to do Milah to their son at the time of Shechitah (while they were in prison), their uncircumcised son did not prevent them from doing the Shechitah. When they are released from prison and are able to circumcise their son, they may not eat the Korban Pesach until they do Milah to their son.
Why does Rava explain that the Beraisa refers to a case in which both the father and mother were in prison at the time of the Shechitah? The Torah states that having an uncircumcised son prevents only the father from eating the Korban Pesach; it makes no mention of the mother. Moreover, the Gemara in Kidushin (29a) states that the mother has no obligation to circumcise her son; the responsibility of Milah rests solely on the father. Rava does not need to mention that both the father and the mother were in prison; it would suffice to say that the father alone was in prison. (MAHARSHA, TESHUVOS TASHBETZ 3:8, OR ZARU'A 2:96)
ANSWERS:
(a) The OR ZARU'A and RABEINU AVRAHAM MIN HA'HAR explain that Rava indeed does not need to mention the whereabouts of the mother. He mentions that she was also in prison only because under normal circumstances -- when the father is unavailable -- the mother takes upon herself the responsibility to do Milah to her son (as the Torah describes in the case of the Milah of the son of Moshe Rabeinu, which Tziporah performed (Shemos 4:25); see also Shabbos 134a). Accordingly, Rava mentions that the mother was in prison only for practical considerations; he needs to explain how the child was still an Arel on the night of Pesach.
The Or Zaru'a, however, is perplexed by Rashi's words. Rashi writes that "the Mitzvah of Milah is upon them," which implies that the mother is obligated to do the Milah just as the father is obligated.
(b) The Or Zaru'a suggests that Rava adds the word "Imo" ("his mother") only as an aside; what matters is that the father was in prison. Rava adds "Imo" simply because the same expression, "his father and his mother were incarcerated," is used in Chulin (11b), where it is necessary to mention that the mother was also imprisoned. Rava here borrows that wording.
(c) RAV YAKOV EMDEN suggests that Rava means that either the father or the mother was in prison. The father's incarceration prevents the Milah from being performed because the father is the one responsible to perform the Milah, and he is unavailable. The mother's incarceration presents the Milah from being performed because the mother is the one who tends to the needs of the baby after the Milah and helps him recuperate. Without her, the baby's life is in danger. Hence, without the mother the father is unable to perform the Milah.
(d) Rashi's words seem contradictory. Rashi implies that both the father and the mother are obligated to do Milah to their son. However, in the end of his comment he writes, "If they left the prison at the time of the eating [of the Korban Pesach], his son prevents him from eating the Korban." Why does Rashi first refer to both parents, and then refer only to the father?
Apparently, Rashi agrees with the other Rishonim who maintain that having an uncircumcised son prevents only the father from eating the Korban Pesach. However, if the father alone would be in jail, he could still eat the Korban Pesach by having his wife perform the Milah. If, in that situation, his wife fails to circumcise the child, it is considered as though he was negligent in his responsibility to circumcise the child, either because he did not send a messenger to his wife or because he did not emphasize the importance of performing Milah before he was separated from his wife. (Similarly, if there is someone else whom the father knows who could take responsibility for the Milah on his behalf and the father neglects to ask that person to do it, his incarceration does not constitute a situation of "Ones" which would permit the father to eat the Korban Pesach while his son is uncircumcised.)
This explains why Rashi writes that "they" are obligated to perform the Milah. Rashi means that the father must either do it himself or have his wife do it on his behalf. If the Milah is not performed, only the father suffers the consequences, and only he is prohibited from eating the Korban Pesach because of his uncircumcised son. (M. Kornfeld)
3) AGADAH: TWO ELEMENTS OF MILAH
The Gemara relates that Avraham Avinu was commanded only to perform Milah but not Peri'ah (removal of the thin membrane after the Orlah is removed). Based on this Gemara, the BEIS HA'LEVI (Parshas Lech Lecha) explains the wording of the verse in the Torah which relates Hash-m's commandment to Avraham Avinu to perform Milah.
Hash-m said to Avraham Avinu, "Go before Me and be complete" (Bereishis 17:1), and, "I will place My covenant between Me and you" (17:2). Why does Hash-m open with a command instructing Avraham Avinu what to do ("Go before Me..."), and then continue with a description of what He will do in the future ("I will place My covenant...")? Why does Hash-m not phrase His second statement in the form of a command as well, such as "Fulfill My covenant"?
The Beis ha'Levi explains that Milah and Peri'ah serve different purposes. Milah, the removal of the Orlah, represents the removal of an imperfection from the person. The Orlah is considered a Mum, a blemish, on the body. The Mishnah in Nedarim (31b, cited here on 71a) states that the Orlah is loathsome and thus wicked people are referred to as "Arelim."
However, Milah accomplishes more than just the removal of an abhorrent blemish. It adds Kedushah to the Jew by forging a bond between Hash-m and him. This is the aspect of Milah to which the Gemara refers when it says, "Great is Milah, because thirteen covenants were established upon it" (Nedarim 31b). This second element of Milah is accomplished by the Peri'ah.
This is the meaning of the verse. Hash-m first told Avraham Avinu, "Go before Me and be complete" -- remove the blemish of Orlah. Hash-m then told Avraham Avinu that although the command to perform Peri'ah has not yet been given, nevertheless "I will place My covenant between Me and you" -- in the future, Hash-m will make a special covenant between Him and Avraham's descendants, through which He will give them Kedushah. This would occur at the time they receive the Mitzvah of Peri'ah (upon entering Eretz Yisrael).