Explanation: Below, we establish it when it is breached to a Karmelis.

Pesak: It seems that the Halachah follows Rav in Isurim, and even if it was breached to a Karmelis, the Halachah follows R. Yosi, who is stringent. (It seems that Tosfos had the Bach's text, in which Rav Chiya bar Yosef said in the name of Rav that the Halachah follows R. Yosi.)

When there are walls, even R. Yosi agrees. He says that since Shabbos was permitted, it was permitted, like we said above (17a).

Explanation: He asks from the Beraisa, because from our Mishnah, which taught "further, R. Yehudah taught that were Me'arev in a Mavuy Mefulash", we do not hear [that he holds that two walls make a Reshus ha'Yachid mid'Oraisa] in a full Reshus ha'Rabim.

Implied question: This Perek should have been taught in Maseches Shabbos, regarding Hotza'ah!

Answer #1: It is because the Seifa taught "R. Yehudah says, one gives to his friend, and his friend to his friend, and even outside the Techum."

Answer #2: It taught at the end of our Perek (105a), R. Shimon says "wherever Chachamim permitted you, they permitted you from yours", and the Gemara explains that he refers to 52b (the Techum is marked 15 Amos before it really ends, due to people who err).

Reference: In Beitzah (15a) it is proven that we discuss when they are not guarded from dogs. However, if they are guarded from dogs, even though they are not guarded from thieves, he may not [enter them].

Explanation: It is also forbidden, for below (97a) a Beraisa forbids [taking] new ones.

Implied question: A Beraisa below (96b) explicitly teaches "R. Meir says, he enters them one pair at a time." We could have asked a contradiction in R. Meir!

Answer: He prefers to challenge our Mishnah. Based on what the Beraisa taught "R. Meir says, he enters them one pair at a time", he could not prove that our Mishnah is R. Meir, like is proven below regarding [the case] of Shabbos, and to ask a contradiction in R. Meir;

Just the contrary, below it is proven that our Mishnah is not R. Meir, for our Mishnah teaches "what is the case? They are old?", and the Beraisa teaches "R. Meir says, the law of new and old is the same."

Explanation #1 (Rashi): This is why it is permitted, but one may not save more than the Mitzvah.

Question: If due to this he comes to deduce one pair [at a time], but not more, if so, below, that it says "really, it is not Zman Tefilin", likewise we could say "really, it is Zman Tefilin"!

Explanation #2: If it is Zman Tefilin, there is Bal Tosif, even if he does not intend, like Rava concludes in Rosh Hashanah (28b). Therefore, [he may take only] one pair [at a time], but not more.

Explanation #1 (Rashi): If [one wears Tefilin] not in the place of Tefilin, they stick out too much. Therefore, it is forbidden.

Rebuttal: This is unreasonable!

Explanation #2: Rather, it is because it is called wearing only in the place that it is normal to wear them during the week.

Question: The Ri was unsure what is the Shi'ur for the width of Tefilin. Some make them big and wide, and some make them very thin.

Inference: Since [the Gemara] said that there is room on the head for two Tefilin, this implies that the Shi'ur of the width fills the place of the two.

Answer (Ri): A Midrash says that their Shi'ur is two fingers. A support is the Tzitz, which was two fingers wide, like it says in Sukah (5a). (Yefei Einayim - the Rosh brings this from Shimusha Raba, an old treatise collection of Hilchos Tefilin. The text of Tosfos should say "Shimusha Raba", in place of "Midrash". Alternatively, he calls Shimusha Raba a Midrash.)

We say in Erchin (3b) that his hair was seen between the Tzitz and the Mitznefes, and there he wore Tefilin, and it seems that the Tzitz was in a place proper to wear Tefilin. (Rosh, Hilchos Tefilin - presumably, just like the Tzitz was two fingers wide, so was the place of Tefilin);

Implied question: Regarding the Tzitz it is written "his forehead", and the Targum is "between his eyes" (which is not a Kosher place for Tefilin)!

Answer: Also regarding Tefilin, it says "between your eyes", and we expound on the height of the head.

Explanation #1: This is the collection of flesh on the arm between the elbow and the shoulder, like Kibura d'Ahini (a cluster of dates). This is unlike the one who explains that...

Explanation #2: Kibores is the collection of flesh between the hand and the elbow, near the elbow.

Rebuttal #1: Everywhere, it connotes that Tefilin is on the Zero'a, and in Ohalos (1:8) it connotes that Zero'a is between the elbow and the shoulder;

It says that there are 30 [bones] in the hand... two in the Kaneh (lower arm), two in the elbow, one in the Zero'a, and four in the shoulder.

Rebuttal #2: Also in Menachos (37b) we say that we require putting [Tefilin] next to the heart.