Talmud for Berakhot 3:1
מלאכה מביא חטאת. שנים מביא אשם תלוי. שלשה פטור. רבי יוסי בר' בון בעי אין תימר שנים ספק ראה שני כוכבים בערב שבת והתרו בו ועשה מלאכה ראה שני כוכבים במוצאי שבת והתרו בו ועשה מלאכה מה נפשך אם הראשונים יום הן אף האחרונים יום הן ויהא חייב על האחרונים אם האחרונים לילה אף הראשונים לילה ויהא חייב על הראשונים. ראה שני כוכבים בערב שבת וקצר כחצי גרוגרת בשחרית וקצר כחצי גרוגרת ראה שני כוכבים במוצאי שבת וקצר כחצי גרוגרת מה נפשך אם הראשונים יום הן אף האחרונים יום הן ויצטרף של שחרית עם של מוצאי שבת ויהא חייב על האחרונים אם האחרונים לילה אף הראשונים לילה ויצטרף של שחרית עם של לילי שבת ויהא חייב על הראשונים. הדא דתימר באילין דלית אורחתהון מתחמיא ביממא ברם באילין דאורחהון מתחמיא ביממא לא משערין בהון. א"ר יוסי בר' בון ובלחוד דיתחמון תלתא כוכבין בר מן הדא כוכבתא. רבי יעקב דרומנה בשם רבי יהודא בן פזי כוכב אחד ודאי יום שנים לילה. ולית ליה ספק. אית ליה ספק בין כוכב לכוכב. תני כל זמן שפני מזרח מאדימים זהו יום
a creative task, he should bring a sin offering. Two--he should bring a conditional sin offering. Three--he is exempt [from bringing a sacrifice of any sort.]” Rabbi Yose bar Bon raised the question [thus]: “If you were to say that two [stars indicate] doubt [as to whether it is day or night, then] if one saw two stars on the eve of the Sabbath and [others] warned him [that it was the Sabbath, thus making him liable for its violation], yet he [nonetheless] performed a creative task; [and if he subsequently] saw two stars on the departure of the Sabbath and [others] warned him [that it was still the Sabbath], yet he performed a creative task; then either way you like [he is liable for a violation of the Sabbath]. If the first [set of stars] were [an indication that it was still] daytime [and not yet the Sabbath], then the last stars were also [an indication that it was still] daytime [and still the Sabbath], then he is liable [for a violation of the Sabbath] on account of the last set [of stars]. If the last [set of stars] were [an indication that it was now] night time [and the Sabbath had begun], then the first stars were also [an indication that it was now] night time [and no longer the Sabbath], then he is liable [for a violation of the Sabbath] on account of the first set [of stars]. [Another example:] If he saw two stars on the eve of the Sabbath and partially harvested a fig, [and] if he [subsequently returned] in the morning and harvested another part, and if he saw two stars on the departure of the Sabbath and harvested the [last] part of the fig, then either way you like [he is liable for a sin offering]. If the first [set of stars] were [an indication that it was still] daytime [and not yet the Sabbath], then the last stars were also [an indication that it was still] daytime [and still the Sabbath] and the morning harvest joins with that of the departure of the sabbath, and he is liable [for a sin offering] on account of the last set [of stars]. If the last [set of stars] were [an indication that it was] night time [and now the Sabbath], then the last stars were also [an indication that it was] daytime [and no longer the Sabbath] and the morning harvest joins with that of the night of the Sabbath, and he is liable [for a sin offering] on account of the first set [of stars].” These [stars] that you are speaking of are [only] those whose way is not to appear in the daytime. However, we do not count those whose way is to appear in the daytime. Rabbi Yose bar Bon said: “Just so long as three stars may be seen aside from that [one we call] Kokhvata (prob. Venus).” (This may be a scribal error and the original version may have been: “Just so long as three stars may be seen [in one place, just] as one star [can be so seen.]”) Rabbi Yaakov of Romana in the name of Rabbi Yehuda ben Pazi: “One star, surely day. Two, night.” But does he [truly] have no [time period of] doubt!? He has doubt about [discerning] one star from another. A baraita teaches: “So long as the eastern horizon is reddened, it is daytime. What has been said about the stars, applies to those which are not generally seen until nightfall; for, no note is taken of those which appear before the day is terminated. Therefore, R. Yosse bar R. Aboon says: It means three stars not counting, R. Jacob from Darom (south) says: One star indicates that it is still day; but two stars certainly show that it is night. Is there any doubt of this? No; the doubt can only exist between the stars visible by day, and the other stars. With regard to this, we are taught that it is still day as long as the sky is red towards the east;
Jerusalem Talmud Yoma
An emission of semen pollutes, but it is a minor impurity which is removed by immersion in water and, for sancta, the following sundown. But gonorrhea and menstruation cause severe impurity for which immersion is possible only after seven days (Lev. 15:13,19). An immersion because of emission, before the time where immersion for the severe impurity is possible, is totally ineffective.
A different version of the following discussion is in Berakhot 3:6, Notes 260–264.: “the woman who started menstruating while having intercourse, needs immersion, but Rebbi Jehudah declares them not liable.” Why does Rebbi Jehudah disagree? Is it about immersion of discipline or because even if he immerses himself what would be its use? What is the difference? If he66The male sufferer from gonorrhea, mentioned in the Mishnah. He had an emission before he started suffering from gonorrhea. He was obligated for an immersion before he became severely impure. had an emission. If you say that Rebbi Jehudah disagrees about immersion of discipline, it is a word of the Torah67Lev. 15:16.. If you say, even if he immerses himself, what would be its use? It is useful that he immerse himself, as it was stated, Rebbi Jehudah says, they instituted this immersion only as immersion of discipline, for sometimes when a person goes to wash he remembers an old emission of semen which he had and turns back. This implies that Rebbi Jehudah did not disagree about immersion of discipline but because even if he immerses himself, what would be its use?