unless it is a case where one exchanges an inner passage for an outer one, e.g., he placed the passage of Exodus 13:11–16 to the right of Exodus 13:1–10, or an outer passage for an inner one, e.g., he placed the passage of Deuteronomy 11:13–21 to the right of Deuteronomy 6:4–9. But if one exchanges an inner passage for the other inner one, i.e., he exchanges Exodus 13:11–16 with Deuteronomy 6:4–9, or an outer passage for the other outer one, i.e., he exchanges Exodus 13:1–10 with Deuteronomy 11:13–21, we have no problem with it.

Rava said to Abaye: What is different about the cases of exchanging an inner passage for an outer one, and an outer passage for an inner one, such that the phylacteries are not fit? The reason is that this passage, which needs to see the air, i.e., to be placed on the outer side, does not see it, and that passage, which does not need to see the air, does see it. But in a case where one exchanges an outer passage for the other outer one or an inner passage for the other inner one, it should be unfit as well, as this passage, which needs to see the air of the right side, sees the air of the left side, and that passage, which requires to see the air of the left side, sees the air of the right side. Rather, there is no difference between any of these cases, and any change in the order renders the phylacteries unfit.

§ And Rav Ḥananel says that Rav says: The requirement to have the titora of phylacteries, i.e., the base of phylacteries upon which the compartments rest, is a halakha transmitted to Moses from Sinai. Abaye said: The requirement to have the ma’ebarta of phylacteries, i.e., the passageway through which the straps are inserted, is a halakha transmitted to Moses from Sinai. And Abaye says: The requirement to have a letter shin protruding on the phylacteries of one’s head, which is achieved by pressing the hide into the shape of that letter, is a halakha transmitted to Moses from Sinai.

Abaye further says: And there is a requirement that the furrow between each of the compartments of phylacteries of the head reach the place of the stitches, i.e., the titora, to which the compartments are sewn. Rav Dimi of Neharde’a says: Once it is noticeable that there is a furrow between each of the compartments, it is not necessary for them to reach all the way to the titora.

And Abaye says: With regard to this parchment upon which one writes the passages of phylacteries, the scribe must examine it before writing, as perhaps it has a flaw, i.e., a perforation, and complete writing is required, and that requirement would not be fulfilled if a letter were perforated. Rav Dimi of Neharde’a says: No prior examination is required; rather, the quill examines it as one writes, as any perforation which the ink covers is disregarded.

Rabbi Yitzḥak says: The requirement that the straps of the phylacteries be black is a halakha transmitted to Moses from Sinai. The Gemara raises an objection from a baraita: One may tie phylacteries only with straps of their same type, i.e., the straps must be made from hide, and it does not matter whether they are green, or black, or white. Nevertheless, one should not make red straps, because this is deprecatory to him, as it looks like he has wounds on his head, and also due to something else, i.e., lest people suspect him of engaging in sexual intercourse with a menstruating woman and getting blood on the straps.

The Gemara cites the continuation of that baraita. Rabbi Yehuda said: There was an incident involving Rabbi Akiva’s student, who would tie his phylacteries with strips of sky-blue wool rather than hide, and Rabbi Akiva did not say anything to him. Is it possible that that righteous man saw his student doing something improper and he did not object to his conduct? Another Sage said to Rabbi Yehuda: Yes, it is possible that the student acted improperly, as Rabbi Akiva did not see him, and if he had seen him, he would not have allowed him to do so.

The baraita continues: There was an incident involving Hyrcanus, the son of Rabbi Eliezer ben Hyrcanus, who would tie his phylacteries with strips of purple wool, and his father did not say anything to him. Is it possible that that righteous man saw his son doing something improper and he did not object to his conduct? The Sages said to him: Yes, it is possible that his son acted improperly, as Rabbi Eliezer did not see him, and if he had seen him, he would not have allowed him to do so. This concludes the baraita.

The Gemara explains the objection from the baraita: In any event, the baraita teaches that it does not matter whether the straps are green, or black, or white, whereas Rabbi Yitzḥak maintains that it is a halakha transmitted to Moses from Sinai that the straps of the phylacteries must be black. The Gemara answers that it is not difficult. Here, the baraita is referring to the inside of the straps, which touch the body. These may be any color other than red. Conversely, there, when Rabbi Yitzḥak says that the straps of the phylacteries must be black, he is speaking of the outside of the straps.

The Gemara raises a difficulty: If the baraita is discussing the inside of the straps, what deprecatory matter or problem of something else is there with straps that are red on the inside? After all, this side is not seen. The Gemara answers: Sometimes his straps become reversed, and therefore these concerns are applicable.

It is taught in a baraita: The requirement that phylacteries be square is a halakha transmitted to Moses from Sinai. Rav Pappa says about this halakha: Square means along their seams and their diagonals, i.e., they must be perfectly square where the compartments are sewn to the titora.

The Gemara suggests: Let us say that a mishna supports this opinion (Megilla 24b): One who fashions his phylacteries in a round shape exposes himself to danger, and it does not enable him to fulfill the mitzva of phylacteries. Rav Pappa said: This is no support, as one can say that the mishna is referring to phylacteries that are fashioned like a nut, i.e., their underside is rounded, and therefore there is a danger that if he strikes his head on a wall the underside will press into his head and injure him. By contrast, if the underside is flat one might have thought that it is fit despite the fact that it is not square. Therefore, the baraita teaches that phylacteries must be square.

§ Rav Huna says: With regard to phylacteries of the head, as long as the surface of outer hide is intact, i.e., it is not torn, they are fit, even if the hide between the compartments has torn. Rav Ḥisda says: If two of the walls between the compartments tore, such phylacteries are fit, but if three of these inner walls tore, they are unfit.

Rava said: Concerning that which you said, that if two of the walls between the compartments tore they are fit, we said this only if the inner walls that tore are not aligned with each other, i.e., they are not adjacent to one another. But if the torn walls are aligned with each other, the phylacteries are unfit. And furthermore, even in a case where the torn walls are aligned with each other, we said that they are unfit only with regard to new phylacteries, as the hide is certainly defective. But with regard to old phylacteries, we have no problem with it, as they tore due to aging.

Abaye said to Rav Yosef: What are the circumstances of new phylacteries, and what are the circumstances of old phylacteries? Rav Yosef said to him: In any case where if one holds the hide and pulls it, it returns to its place [ḥaleim], these phylacteries are considered old; and in the other case, where hide that was pulled does not return to its place, they are considered new.