Menachot 43a:15-20
בן ארבעים יום ותרי לה בגווייהו מאורתא ועד לצפרא איפרד חזותיה פסולה לא איפרד חזותיה כשרה that was forty days old. He would soak the sky-blue wool in this solution from night until morning. If its color would fade [ipparad ḥazutei], the sky-blue wool was determined to be unfit, as it was not dyed with tekhelet derived from a ḥilazon. If its color would not fade, the sky-blue wool was determined to be fit.
ורב אדא קמיה דרבא משמיה דרב עוירא אמר מייתי חמירא ארכסא דשערי ואפיא לה בגוויה אישתנאי למעליותא כשרה לגריעותא פסולה וסימניך שינוי שקר שינוי אמת And Rav Adda said before Rava in the name of Rav Avira: One brings hard [arkesa] leavened barley dough and bakes the sky-blue wool in it. If the color of the sky-blue wool changes for the better, meaning that the process intensifies the color of the sky-blue wool, then it is fit. If the color of the sky-blue wool changes for the worse, i.e., it fades, then it is unfit. And your mnemonic is: Change reveals falsehood and change reveals truth. All of this indicates that it is possible to test whether sky-blue wool has been dyed with real tekhelet, contrary to the baraita.
מאי אין לה בדיקה נמי דקאמר אטעימה The Gemara explains the baraita: What does it mean when it says: There is no reliable method of testing sky-blue wool? It means that there is no way to test whether it was dyed for the sake of the mitzva or for the purpose of testing the dye.
מר ממשכי אייתי תכלתא בשני רב אחאי בדקוה בדרב יצחק בריה דרב יהודה ואיפרד חזותיה בדרב אדא ואישתנאי למעליותא The Gemara relates that Mar, a Sage from Mashkhei, brought sky-blue wool in the years when Rav Aḥai was a preeminent Sage. They tested it in the manner described by Rav Yitzḥak, son of Rav Yehuda, and its color faded. They then tested it in the manner described by Rav Adda and the color changed for the better.
סבר למיפסלה אמר להו רב אחאי אלא הא לא תכילתא היא ולא קלא אילן היא אלא שמע מינה שמועתא אהדדי איתמר The Sages thought that the sky-blue wool should be deemed unfit because it did not pass the first test. Rav Aḥai said to them: But how could it be that this wool is not tekhelet, as it failed one of the tests, and is also not indigo, as it passed the other? This is impossible, because it must be one or the other. Rather, conclude from it that these halakhot were stated together.
היכא דבדקנא בדרב יצחק בריה דרב יהודה לא איפרד חזותיה כשרה איפרד חזותיה בדקינן לה בדרב אדא בחמירא ארכסא אישתני למעליותא כשרה לגריעותא פסולה שלחו מתם שמועתא אהדדי איתמר He explains: In a case where we tested the wool in the manner described by Rav Yitzḥak, son of Rav Yehuda, and its color did not fade, it is fit and requires no further testing. If its color faded, then we test it in the manner described by Rav Adda, with hard leavened barley dough. If the color changed for the better it is fit; if the color changed for the worse it is unfit. The Gemara adds: They sent a message from there, i.e., Eretz Yisrael: These halakhot were in fact stated together, as explained by Rav Aḥai.
רבי מני דייק וזבין כחומרי מתניתא א"ל ההוא סבא הכי עבוד קמאי דקמך ואצלח עיסקייהו The Gemara relates that Rabbi Mani was exacting and purchased sky-blue wool in accordance with the stringencies of the baraita cited earlier, i.e., that wool dyed as a test is unfit for ritual fringes, and that therefore one should purchase sky-blue wool for ritual fringes only from an expert. A certain elder said to him: This is what your early predecessors did, and their businesses were successful.
ת"ר הלוקח טלית מצוייצת מן השוק מישראל הרי היא בחזקתה מן העובד כוכבים מן התגר כשרה מן ההדיוט פסולה The Sages taught in a baraita: In the case of one who purchases a cloak with ritual fringes from the marketplace, if he purchased it from a Jew it retains its presumptive status that it is fit for the mitzva. If he purchased it from a gentile, then if he purchased it from a merchant it is presumed to be fit, as the merchant would want to maintain his credibility and would therefore purchase the sky-blue strings only from a reliable source. But if he purchased it from a gentile who is an ordinary person rather than a professional merchant, the sky-blue strings are unfit, as the seller presumably dyed them himself.
ואע"פ שאמרו אין אדם רשאי למכור טלית מצוייצת לעובד כוכבים עד שיתיר ציציותיה And even though the Sages said: A person is not permitted to sell a cloak with ritual fringes to a gentile until he unties and removes its ritual fringes, it is permitted to purchase such a cloak from a gentile merchant, as it is assumed that the merchant acquired the cloak from a Jew who ignored this halakha.
מאי טעמא הכא תרגימו משום זונה רב יהודה אמר שמא יתלוה עמו בדרך ויהרגנו The Gemara asks: What is the reason for the prohibition against selling a cloak with ritual fringes to a gentile? The Gemara answers: Here they interpreted that it is prohibited because of the concern that the gentile will visit a prostitute and observers will think that he is a Jew. Alternatively, Rav Yehuda said: It is prohibited lest a Jew mistake the gentile for a Jew and accompany him on a journey thinking that he is also Jewish, due to his ritual fringes, and the gentile might then kill him.
רב יהודה רמי תכילתא לפרזומא דאינשי ביתיה ומברך כל צפרא להתעטף בציצית § Rav Yehuda would affix white and sky-blue strings to the garment [pirzuma] of his wife. And every morning he would recite the blessing: To wrap ourselves in garments with ritual fringes.
מדרמי קסבר מצות עשה שלא הזמן גרמא הוא אמאי מברך כל צפרא וצפרא The Gemara asks: From the fact that he would affix ritual fringes to his wife's garments, it is apparent that he holds that the obligation of ritual fringes is a positive mitzva that is not time-bound, and therefore women are also obligated in it. But if that is his opinion, why did he recite the blessing on ritual fringes each and every morning? In order for the mitzva to not be time-bound, it must apply at night, in which case a new blessing should not be recited in the morning.
כרבי דתניא תפילין כל זמן שמניחן מברך עליהן דברי רבי The Gemara answers: Rav Yehuda was acting in accordance with the opinion of Rabbi Yehuda HaNasi, as it is taught in a baraita: With regard to phylacteries, every time one dons them he recites the blessing over them, even several times in one day; this is the statement of Rabbi Yehuda HaNasi.
אי הכי כל שעתא נמי רב יהודה איניש צניעא הוה ולא שרי ליה לגלימיה כוליה יומא ומאי שנא מצפרא כי משני מכסות לילה לכסות יום The Gemara asks: If so, he should have also recited a blessing every time that he took the cloak off and put it back on, and not merely once a day in the morning. The Gemara answers: Rav Yehuda was a modest man and he did not remove his cloak the entire day. The Gemara asks: In what way is it different from the morning, i.e., why did he recite a blessing in the morning? The Gemara answers: He recited the blessing in the morning when he changed from a nighttime garment to a daytime garment.
ת"ר הכל חייבין בציצית כהנים לוים וישראלים גרים נשים ועבדים ר"ש פוטר בנשים מפני שמצות עשה שהזמן גרמא הוא וכל מצות עשה שהזמן גרמא נשים פטורות § The Sages taught in a baraita: Everyone is obligated in the mitzva of ritual fringes, including priests, Levites, Israelites, converts, women, and Canaanite slaves. Rabbi Shimon deems women exempt, because the mitzva of ritual fringes is a positive, time-bound mitzva, and women are exempt from every positive, time-bound mitzva.
אמר מר הכל חייבין בציצית כהנים לוים וישראלים פשיטא דאי כהנים לוים וישראלים פטירי מאן ליחייב The Gemara analyzes the baraita. The Master said in the baraita: Everyone is obligated in the mitzva of ritual fringes, including priests, Levites, and Israelites. The Gemara asks: Isn't that obvious? As, if priests, Levites, and Israelites were exempt from the mitzva, who then is to be obligated?
כהנים איצטריכא ליה ס"ד אמינא הואיל וכתיב (דברים כב, יא) לא תלבש שעטנז צמר ופשתים יחדיו גדילים תעשה לך מאן דלא אישתרי כלאים לגביה בלבישה הוא דמיחייב בציצית הני כהנים הואיל ואישתרי כלאים לגבייהו לא ליחייבו The Gemara answers: It was necessary for the baraita to mention that priests are obligated to fulfill the mitzva, as it may enter your mind to say as follows: Since it is written: "You shall not wear diverse kinds, wool and linen together. You shall prepare yourself twisted cords upon the four corners of your covering" (Deuteronomy 22:11–12), only one who is not permitted to wear diverse kinds is obligated in the mitzva of ritual fringes. With regard to these priests, since diverse kinds are permitted for them when they perform the Temple service, as the belt of the priestly vestments contains diverse kinds, they should not be obligated in the mitzva of ritual fringes.
קמ"ל נהי דאישתרי בעידן עבודה בלא עידן עבודה לא אישתרי Therefore, the baraita teaches us that although the prohibition of diverse kinds is permitted for them at the time when they perform the Temple service, when it is not the time of the Temple service it is not permitted, and therefore priests are obligated in the mitzva of ritual fringes.
ר"ש פוטר בנשים מאי טעמא דר"ש דתניא (במדבר טו, לט) וראיתם אותו פרט לכסות לילה The baraita states that Rabbi Shimon deems women exempt. The Gemara asks: What is the reasoning of Rabbi Shimon? The Gemara answers: As it is taught in a baraita that with regard to ritual fringes it is stated: "And it shall be unto you for a fringe, that you may look upon it and remember all the commandments of the Lord" (Numbers 15:39). The term "that you may look" excludes a nighttime garment, as it is dark at night and it is therefore difficult to see.
אתה אומר פרט לכסות לילה או אינו אלא פרט לכסות סומא כשהוא אומר (דברים כב, יב) אשר תכסה בה הרי כסות סומא אמור הא מה אני מקיים וראיתם אותו פרט לכסות לילה The baraita continues: One may ask: Do you say that the verse serves to exclude a nighttime garment? Or is it to exclude only the garment of a blind person, who is also unable to see his ritual fringes? The tanna explains: When the verse states: "Of your covering, with which you cover yourself" (Deuteronomy 22:12), the garment of a blind person is mentioned as being included, as the verse already stated: "Of your covering," and did not need to state: "With which you cover yourself." If so, how do I realize the meaning of the exclusion: "That you may look upon it"? It must exclude a nighttime garment.
ומה ראית לרבות כסות סומא ולהוציא כסות לילה מרבה אני כסות סומא שישנה בראיה אצל אחרים ומוציא אני כסות לילה שאינה בראיה אצל אחרים The Gemara asks: What did you see that led you to include the garment of a blind person from the phrase: "With which you cover yourself," and to exclude a nighttime garment from the phrase: "That you may look upon it," rather than including a nighttime garment in the obligation and excluding the garment of a blind person? The Gemara answers: I include the garment of a blind person, which is visible to others, even though the blind person himself cannot see it, and I exclude a nighttime garment, which is not visible even to others.
ורבנן The Gemara asks: And the Rabbis who disagree with Rabbi Shimon,