Alternatively, in any case where if the phylacteries are hanging by the strap the compartment follows the strap, i.e., it remains attached, these phylacteries are considered new; and in the other case, where the phylacteries would fall off, they are considered old.

§ The Gemara relates: Abaye was sitting before Rav Yosef when the strap of his phylacteries 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 phylacteries: “And you shall bind them [ukshartam] for a sign upon your arm” (Deuteronomy 6:8), which teaches that the binding must be complete [keshira tamma], whole and beautiful, and that would not be the case with a makeshift knot.

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 permitted.

Rav Pappa says: The remnants of straps, i.e., what remains when part of the strap has been cut off, are fit. The Gemara comments: And it is not so, as can be derived from the fact that the sons of Rabbi Ḥiyya say: The remnants of the sky-blue wool of ritual fringes, when only a small thread remains, and likewise the remnants of the hyssop, used for the sprinkling of the purification water of the red heifer, are fit. They did not include the remnants of straps of phylacteries in this halakha. The reason for this difference is that it is there that the remnants are fit, as they are mere articles used in the performance of a mitzva; but here, phylacteries are articles of sanctity, which are of greater sanctity, and therefore their remnants are not fit.

The Gemara states: From this line of inquiry one can conclude by inference that the straps of phylacteries 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 a bowed measure, i.e., from the tip of the middle finger until the tip of the index finger, with the fingers spread. Rav Ashi would demonstrate a straight measure, from the tip of the thumb until the tip of the index finger, with the fingers spread.

The Gemara relates: Rabba would tie the straps and release them and let them fall behind him. Rav Aḥa bar Ya’akov would tie them and plait them together like a braid. Mar, son of Rabbana, would act like we do, i.e., he would let the straps fall and hang over the front of his body.

Rav Yehuda, son of Rav Shmuel bar Sheilat, says in the name of Rav: The form of the knot of phylacteries, i.e., that there must be the form of a letter dalet in the knot of the phylacteries of the head and the letter yod in the knot of the phylacteries of the arm, is a halakha transmitted to Moses from Sinai. Rav Naḥman says: And their decorative side, the black side of the knot where the shape of the letter is visible, must face outward. The Gemara relates: Rav Ashi was sitting before Mar Zutra when the strap of his phylacteries became reversed. Mar Zutra said to him: Doesn’t the Master hold in accordance with the ruling that their decorative side must face outward? Rav Ashi said to him: It did not enter my mind, i.e., I did not notice.

With regard to the verse: “And all the nations of the land shall see that the name of the Lord is called upon you, and they shall be afraid of you” (Deuteronomy 28:10), it is taught in a baraita that Rabbi Eliezer the Great says: This is a reference to the phylacteries of the head, upon which the name of God is written, as they demonstrate to all that the name of God is called upon the Jewish people. With regard to the statement of God to Moses: “And I will remove My hand, and you will see My back” (Exodus 33:23), Rav Ḥana bar Bizna says that Rabbi Shimon Ḥasida says: This teaches that the Holy One, Blessed be He, showed Moses the knot of the phylacteries of the head.

Rav Yehuda says: The knot of phylacteries must be above, i.e., it must rest on the head rather than on the neck, in order that the Jewish people should be above and not below. And likewise it must be placed toward the front [panim], i.e., not on the sides of the head, in order that the Jewish people should be in front [lefanim] and not behind.

§ Rav Shmuel bar Bideri says that Rav says, and some say that Rabbi Aḥa Arikha, i.e., Rabbi Aḥa the Tall, says that Rav Huna says, and some say that Rav Menashya says that Shmuel says: With regard to phylacteries, from when does one recite a blessing over them? From the time when one dons them on the arm and onward. The Gemara raises a difficulty: Is that so? But doesn’t Rav Yehuda say that Shmuel says: With regard to all the mitzvot, one recites a blessing over them prior to their performance? How, then, can one recite a blessing over phylacteries after donning them? Abaye and Rava both say: One recites the blessing from the time of donning the phylacteries until the time of binding them, as the binding constitutes the performance of the mitzva.