חמץ בפסח ויוה"כ דכרת סמכינן אדיסקי הכא דעשה בעלמא לא כל שכן
with regard to the prohibitions against eating leavened bread on Passover and eating on Yom Kippur, which are punishable by karet, we rely on letters sent from the rabbinical court in Eretz Yisrael publicizing whether the year was declared a leap year and when they have declared the New Moon; here, with regard to the mitzva of ritual fringes, which is merely a positive mitzva, is it not all the more so correct that letters can be relied on?
אלא אמר רבא הא מילתא אמרי ואיתמר במערבא משום דרבי זירא כוותי שמא יקרע סדינו בתוך ג' ויתפרנו
Rather, Rava said: This is a statement that I said, and it was stated in the West, Eretz Yisrael, in the name of Rabbi Zeira in accordance with my opinion: The reason for the rabbinic decree is lest one’s cloak rip within three fingerbreadths of the edge of the corner of the garment, which is where the ritual fringes are placed, and he sew it with linen string and then use the excess string for ritual fringes.
והתורה אמרה תעשה ולא מן העשוי
And in such a case the ritual fringes would be unfit because the Torah states: “You shall prepare yourself twisted cords” (Deuteronomy 22:12), which teaches: Prepare it, and not from what has already been prepared. Consequently, the strings must be attached to the garment for the sake of the mitzva of ritual fringes. When the individual places the linen string there in order to stitch the garment and then decides to use it for the mitzva of ritual fringes and adds sky-blue wool strings, he does not fulfill the mitzva of ritual fringes and violates the prohibition against wearing a garment of wool and linen.
שרא רבי זירא לסדיניה רב זירא אמר גזירה נמי משום כסות לילה
Because of this rabbinic decree, Rabbi Zeira untied the ritual fringes and removed them from his linen cloak. Rav Zeira said: The rabbinic decree prohibiting ritual fringes on a linen garment is also due to the concern that one might affix ritual fringes to a nighttime garment. Since the mitzva of ritual fringes does not apply in that case, if one wears the garment he would not fulfill the mitzva and would violate the prohibition against wearing a garment with wool and linen.
ואמר רבא הא מילתא אמרי ואיתמר במערבא משמיה דר' זירא כוותי היא של בגד וכנפיה של עור חייבת היא של עור וכנפיה של בגד פטורה מאי טעמא עיקר בגד בעינן
And Rava said: This is a statement that I said, and it was stated in the West, Eretz Yisrael, in the name of Rabbi Zeira in accordance with my opinion: If a garment is made from cloth and its corners are made from leather, it is required to have ritual fringes. Conversely, if a cloak is made from leather and its corners are made from cloth, it is exempt from the mitzva of ritual fringes. What is the reason for this? We require that the main part of the garment be obligated, and a leather garment is not required to have ritual fringes.
רב אחאי אזיל בתר כנף
The Gemara notes: Rav Aḥai would follow the corner in determining whether the garment is required to have ritual fringes or not, because the Torah states: “On the corners of their garments” (Numbers 15:38).
אמר רבא אמר רב סחורה אמר רב הונא הטיל לבעלת שלש והשלימה לארבע פסולה [משום] תעשה ולא מן העשוי
§ Rava says that Rav Seḥora says that Rav Huna says: In a case where one affixed ritual fringes to a garment possessing only three corners, which is not required to have ritual fringes, and then completed its fourth corner by sewing on additional material or cutting away some of the material, the ritual fringes he attached to the original three corners are unfit. This is due to the principle: Prepare it, and not from what has already been prepared. Once the garment is required to have ritual fringes one may attach the ritual fringes; the strings that were attached before the garment was required to have them are not fit.
מיתיבי חסידים הראשונים כיון שארגו בה ג' היו מטילין לה תכלת אימא כיון שפצעו בה ג' היו מטילין לה תכלת
The Gemara raises an objection from a baraita: It is told of the early generations of pious men that once they weaved three fingerbreadths of the length of the garment, they would affix the white and sky-blue strings to the first two corners, even though the garment was not yet long enough to be obligated to have ritual fringes. The Gemara answers: Say that the baraita should read as follows: Once they completed [shepatzu] the garment until there were only three fingerbreadths left to weave, they would affix the white and sky-blue strings to the first two corners.
ומי אמרינן תעשה ולא מן העשוי (איני) והאמר ר' זירא הטיל למוטלת כשרה
The Gemara asks: And do we say: Prepare it, and not from what has already been prepared? Is that so that this principle disqualifies ritual fringes that one affixed to a garment before he was required to do so? But doesn’t Rabbi Zeira say: If one affixed ritual fringes to a garment that already had ritual fringes affixed to it and then removed the original strings, it is fit, despite the fact that when he attached the second set they were superfluous? This indicates that even if one attaches ritual fringes to a garment when there is no obligation to attach them, the ritual fringes are fit.
אמר רבא השתא בבל תוסיף קאי מעשה לא הוי
Rava said: This does not present a difficulty, because now that he adds a second, unnecessary set of ritual fringes and is liable for violating the prohibition of adding to a mitzva (see Deuteronomy 13:1), is it not considered an action?
מתקיף לה רב פפא ממאי דגברא לאוסופי קא מיכוין דלמא לבטולי קא מיכוין ובל תוסיף ליכא מעשה איכא
Rav Pappa objects to this: From where is it known that Rabbi Zeira is discussing a case where the person intended to add to the original set of ritual fringes? Perhaps Rabbi Zeira is discussing a case where he intended to nullify the original strings, and therefore there is no prohibition of adding to a mitzva, and there is an action.
אמר ר' זירא אמר רב מתנא אמר שמואל תכלת אין בה משום כלאים ואפי' בטלית פטורה
With regard to the issue of affixing ritual fringes to a garment that already has ritual fringes, the Gemara relates: Rabbi Zeira says that Rav Mattana says that Shmuel says: White and sky-blue strings are not subject to the prohibition of diverse kinds, and this is the halakha even if they are affixed to a cloak that is exempt from ritual fringes.
מאי טלית פטורה אילימא דלית בה שיעורא והתניא טלית שהקטן מתכסה בו ראשו ורובו
The Gemara asks: What is meant by: A cloak that is exempt from ritual fringes? If we say that it is referring to a cloak that is not of the size necessary to require the affixing of ritual fringes, that is difficult: But isn’t it taught in a baraita: With regard to a cloak that is large enough for a minor to cover his head and most of his body with it,