Gemara

2a (Mishnah): One who brings a Get from abroad (Chutz la'Aretz) must say 'Befanai Nichtav u'Befanai Nechtam (it was written and signed in front of me).'

R. Shimon ben Gamliel requires this even if he brings from one county to another.

Question: Why was this enactment made?

Answer #1 (Rabah): It was because people in Chutz La'aretz do not know that a Get must be written Lishmah (with intent to divorce that woman).

Answer #2 (Rava): It was lest the Get be contested, and witnesses will not be readily available to be Mekayem it (verify the signatures).

3a - Question: Rabah says that the concern is that people are ignorant of the law of Lishmah. The Shali'ach must testify about the writing and signing of the Get. Which Tana requires both of these to be Lishmah?

4a - Answer (Rav Ashi): The Mishnah is like R. Yehudah, who disqualifies a Get if it was written or signed when attached.

4b: Rabah agrees that we are concerned for Kiyum. He is also concerned for Lishmah. They differ about two Sheluchim who bring a Get, and a Get brought within one county in Chutz La'aretz. (Only Rabah requires a declaration.)

5b: R. Yehoshua ben Levi is concerned for Lishmah, and R. Yochanan is concerned only for Kiyum.

Bar Hedya wanted to bring a Get. R. Achai said that he must see every letter written. R. Ami and R. Asi said that this is unnecessary, and he should not do so, lest people doubt the validity of previous Gitin, for which this was not done.

Rabah bar bar Chanah brought a Get. R. Elazar said that it suffices if he saw the first line written Lishmah. Rav Ashi said that hearing the pen scratching on the paper suffices.

(Beraisa): A Get from abroad is Kosher even if he went in and out all day.

Even if the scribe went to the market, we are not concerned lest another man asked the scribe to write the Get for him (and it is Lo Lishmah).

15a (Mishnah): A Get from Chutz la'Aretz is Pasul if the Shali'ach said 'in front of me it was totally written, and half was signed'; or vice-versa.'

Opinion #1 (Rav Chisda): When a Shali'ach saw all the writing and one signature, even if two testify about the other signature, it is Pasul. We require standard Kiyum (two witnesses for each signature), or totally like Chachamim's enactment.

Opinion #2 (Rava): Even if the Shali'ach and another person testify about the other signature, it is Pasul. We decree lest people think that a witness can confirm his own signature, and help to confirm the other. This Kiyum is Pasul, since three fourths of it relies on one witness.

Opinion #3 (Rav Ashi): Even if the Shali'ach is the other witness, it is Pasul. The Kiyum must be totally like normal Kiyum, or totally like Chachamim's enactment.

17a (Mishnah): If one says 'it was written in front of me' and two say 'it was signed in front of us', it is valid.

(R. Ami, citing R. Yochanan): Even when the witnesses about the signing are the Sheluchim, it is valid (even though there is only one witness about the writing).

Inference: He exempts two Sheluchim that bring a Get from a declaration.

Objection (R. Asi): Another time, you said differently!

Answer: (R. Ami): Do not veer from this latter version. It is correct.

Rishonim

Rif and Rosh (1:2): The Sugya is like Rava. One must say Befanai Nichtav u'Befanai Nechtam only where there are not witnesses for Kiyum.

Ran (DH Bar and DH Afilu): The Ra'avad proves from Bar Hedya and R. Elazar that we rule like Rabah. However, even Rava could require seeing every letter, since we require testimony about Lishmah to distinguish from normal Kiyum. He could obligate seeing the first line, i.e. the line that must be Lishmah, in order that he can say Befanai Nichtav u'Befanai Nechtam.

Ra'avad (in Sefer ha'Zechus): The Sugya is like Rabah. A Beraisa teaches that if a scribe went in and out, we are not concerned lest another man requested a Get, and this Get is Lo Lishmah. If a Shali'ach testified about the entire signing and half the writing, it is Pasul, like Rabah. We will not confuse it with normal Kiyum. Rava must say that we decree due to vice-versa. We follow R. Yehoshua ben Levi, who holds like Rabah, against R. Yochanan.

Rebuttal (Sefer ha'Zechus): The entire Sugya is like Rava. Rav Ashi, who is Basra, said that Rabah must establish the Mishnah to be like R. Yehudah. Since we rule like R. Elazar, and not R. Yehudah, the Halachah does not follow Rabah. The final version of R. Ami, which one may rely on, is like Rava. Rav Chisda, Rava and Rav Ashi discuss what Kiyum suffices when the Shali'ach saw all the writing and half the signatures. This is only like Rava. It cannot be like Rabah, even after they learned, for he holds that partial testimony about the signatures is nothing. Surely, the Shali'ach saw only half because they did not sign together. Perhaps in the middle the husband reconsidered, and decided to divorce his other wife with the same name!

Hasagos ha'Ra'avad: Why is Rabah concerned only for Lishmah? Many other things disqualify a Get, e.g. it was written during the day and signed at night, it was written attached and needed to be detached before giving it, relatives or Pasul witnesses signed it, the witnesses did not sign in front of each other, or he did not command the scribe to write or the witnesses to sign. If people are ignorant about Lishmah, all the more so they are ignorant about these! We must say that the above Pesulim are not common, therefore Rabah is not concerned for them. Why are we not concerned when there are two Sheluchim? Since the husband gave it to them, they are like Edei Mesirah, so the Get is Kosher even without Edei Chasimah. We disqualify Mezuyaf Mitocho (a Get with invalid witnesses) only when we know that the witnesses are Pasul. Here it is only a Safek. Alternatively, since he gave it to two, we are not concerned lest he come and protest.

Rambam (Hilchos Gerushin 7:8): Chachamim obligated a declaration in Chutz la'Aretz, lest a woman need Kiyum if her husband will come and protest, because witnesses are not available for Kiyum from place to place in Chutz la'Aretz.

Poskim

Shulchan Aruch (EH 142:1): If a Shali'ach brought a Get from place to place in Chutz la'Aretz, or from Eretz Yisrael to Chutz la'Aretz or vice-versa, if he was present when they wrote and signed the Get, he says in front of two Befanai Nichtav u'Befanai Nechtam, and then gives to her in front of them. If the Shali'ach was not present when they wrote and signed it, he may give it to her only if the signatures are validated. This was required so she will not need to validate it if her husband will come and protest, for witnesses are not available for Kiyum from place to place in Chutz la'Aretz.

Beis Yosef (DH v'Chosav): The Ra'avad rules like Rabah, but the Rif, Rambam and Rosh rule like Rava.