Study Menachot folio 35B with parallel Hebrew-English text, traditional commentary, and modern study tools. Free access to Babylonian Talmud online.
Alternatively, in any case where if the tefillin are hanging by the strap the compartment follows the strap, i.e., it remains attached, these tefillin are considered new; and in the other case, where the tefillin would fall off, they are considered old.
§ The Talmud relates: Abaye was sitting before Rav Yosef when the strap of his tefillin tore. Abaye said to Rav Yosef: What is the halakha as to whether one may tie the strap? Rav Yosef said to him: It is written with regard to tefillin: “And you shall bind them [ukshartam] for a sign upon your arm
Rav Aḥa, son of Rav Yosef, said to Rav Ashi: What is the halakha as to whether one may sew a strap that tore and insert the stitching inside, so that it is not visible from the outside? Rav Ashi said to him: Go out and see what the people are doing. If the common custom is to do this, it is permit
Rav Pappa says: The remnants of straps, i.e., what remains when part of the strap has been cut off, are fit. The Talmud comments: And it is not so, as can be derived from the fact that the sons of R' Ḥiyya say: The remnants of the tekhelet wool of tzitzit, when only a small thread remains, and li
The Talmud states: From this line of inquiry one can conclude by inference that the straps of tefillin have a minimum requisite measure. And how much is their measure? Rami bar Ḥama says that Reish Lakish says: It is until the index finger. In explanation of this size, Rav Kahana would demonstrate