Talmud - Shabbat 79b שבת ע״ט ב׳

We learned in the mishna: The measure that determines liability for carrying out parchment is equivalent to that which is used to write the shortest portion in the phylacteries. And the Gemara raised a contradiction from that which was taught: The measure that determines liability for carrying out parchment and dokhsostos is equivalent to that which is used to write a mezuza on it. The Gemara asks: What is the meaning of mezuza in this context? It means those Torah portions of the mezuza that also appear in the phylacteries. The Gemara asks: And are the phylacteries called mezuza? The Gemara answers: Yes, as it was taught in a baraita: The straps of the phylacteries, when they are with the phylacteries, render the hands ritually impure as is the case with regard to contact with any sacred texts. When they are on their own, they do not render the hands ritually impure. Rabbi Shimon ben Yehuda says in the name of Rabbi Shimon: One who touches the strap of the phylacteries remains ritually pure even if it is attached to the phylacteries, unless he touches the actual box of the phylacteries. Rabbi Zakkai says in Rabbi Shimon’s name: One remains ritually pure until he touches the mezuza itself. Apparently the Torah portions in phylacteries are called mezuza.

The Gemara asks: And from the fact that the latter clause of the mishna teaches: The measure that determines liability for carrying out parchment is equivalent to that which is used to write the shortest portion in the phylacteries, which is the portion of Shema Yisrael, by inference, in the first clause of the mishna we are dealing with a mezuza itself. Rather, this is what it teaches: With regard to parchment and dokhsostos, how much is the measure that determines liability for carrying them out? The measure that determines liability for carrying out dokhsostos is equivalent to that which one uses to write a mezuza on it. The measure that determines liability for carrying out parchment is equivalent to that which one uses to write on it the shortest passage that is in the phylacteries, which is Shema Yisrael.

Rav said: Dokhsostos has the same legal status as parchment: Just as one may write the portions of the phylacteries on parchment, so too, one may write the portions of the phylacteries on dokhsostos. The Gemara asks, we learned in the mishna: The measure that determines liability for carrying out parchment is equivalent to that which is used to write the shortest portion in the phylacteries, which is the portion of Shema Yisrael. By inference: Parchment, yes, the portions of the phylacteries may be written on it. Dokhsostos, no, the portions of the phylacteries may not be written on it. The Gemara answers: That is no proof, as the mishna is referring to the optimal manner in which to fulfill the mitzva, i.e., writing the portions of the phylacteries on parchment. However, one fulfills the mitzva by writing on dokhsostos as well. Come and hear that which was taught in a baraita: It is a halakha transmitted to Moses from Sinai that the portions of the phylacteries are written on parchment, and a mezuza is written on dokhsostos. When writing on parchment, one writes on the side of the hide that faced the flesh; on dokhsostos, one writes on the side of the hide on which there was hair. This contradicts the opinion of Rav, who said that phylacteries may be written on dokhsostos. The Gemara answers: The baraita is also referring to the optimal manner in which to fulfill the mitzva.

The Gemara asks: And wasn’t it taught in a baraita that if one deviated and wrote on something else it is invalid, indicating that the portions of the phylacteries may not be written on anything other than parchment? The Gemara rejects this: This baraita is referring to a mezuza, which is invalid if written on parchment. The Gemara asks: But was it not taught in a different baraita: If one deviated in this, phylacteries, and that, mezuza, it is invalid? The Gemara rejects this: Both this and that are referring to a mezuza, and this additional invalidation is in a case where one deviated and wrote it on parchment, on the side that faced the hair; or, alternatively, where he deviated and wrote it on dokhsostos, on the side that faced the flesh. And, if you wish, say instead: Actually, this and that are referring to phylacteries and a mezuza. However, the halakha with regard to a case where one deviated in this and that is subject to a tannaitic dispute, as it was taught in a baraita: If one deviated in this and that it is invalid. Rabbi Aḥa deems it valid in the name of Rabbi Aḥai bar Ḥanina, and some say in the name of Rabbi Ya’akov, son of Rabbi Ḥanina. Rav Pappa said: Rav said his statement in accordance with the opinion of the tanna from the school of Menashe. As it was taught in the school of Menashe: If one wrote it on paper or on a cloth it is invalid. However, if one wrote it on parchment or on a hide that was treated with gallnuts [gevil] or on dokhsostos it is valid.

The Gemara elaborates: If he wrote it; wrote what? If you say that it is referring to a mezuza, do we write a mezuza on parchment? Rather, isn’t it referring to phylacteries? Apparently, as Rav said, there are Sages who hold that the portions of the phylacteries may be written on dokhsostos. The Gemara rejects this: And according to your reasoning, do we write phylacteries on gevil? Rather, that baraita was taught with regard to a Torah scroll. The Gemara comments: Let us say that the following supports the opinion of Rav: Similarly, phylacteries that became tattered and a Torah scroll that became tattered, one may not make them into a mezuza, despite the fact that identical Torah portions appear in all three. This is prohibited because one does not downgrade from a level of greater sanctity, i.e., a Torah scroll or phylacteries, to a level of lesser sanctity, i.e., a mezuza.

The Gemara infers: The reason that one may not do so is because one does not downgrade. However, if the halakha were that one does downgrade, one would make a mezuza from phylacteries. The Gemara elaborates: On what is the portion of the phylacteries written? Isn’t it written on dokhsostos? This supports the opinion of Rav. The Gemara answers: No, the portion of the phylacteries is written on parchment. The Gemara asks: If so, how could a mezuza be made from it? Do we write a mezuza on parchment? The Gemara answers: Yes, as it was taught in a baraita: If one wrote a mezuza on parchment, or on paper, or on a cloth, it is invalid. Rabbi Shimon ben Elazar said: Rabbi Meir would write it on parchment, as it is thereby better preserved. Apparently, even a mezuza may be written on parchment, and there is no proof from the previous baraita. In reaction to the previous baraita, the Gemara comments: Now that you have arrived at this opinion that a mezuza may be written on both dokhsostos and parchment, according to Rav, as well, do not say: Dokhsostos has the same legal status as parchment with regard to phylacteries; rather, say: Parchment has the same legal status as dokhsostos. Just as on dokhsostos, one may write a mezuza, so too, on parchment, one may write a mezuza, in accordance with the opinion of Rabbi Meir.

We learned in the mishna: The measure that determines liability for carrying out ink is equivalent to that which is used to write two letters.

Traduction : The William Davidson digital edition of the Koren Noé Talmud, with commentary by Rabbi Adin Even-Israel Steinsaltz.

Shabbat 79b examines the minimum parchment size for Sabbath carrying liability, linking mezuza texts to phylactery portions and ritual impurity rules.