Talmud for Niddah 3:1

הרואה דם מטמא למפרע ומה היא מטמא האוכלין והמשקין והמשכבות והמושבות ואינה מקולקלת למניינה ואינה מטמא את בעלה למפרע רבי עקיבה אומר מטמא את בעלה למפרע וזה וזה תולין אבל לא שורפין. תמן אמרין מעת לעת שאמרו משכבה כמגעה מה כבועל נדה ואינו מטמא בהיסט ואינו מטמא ככלי חרס אשכח תני מטמא בכלי חרס בהיסט. מעת לעת שאמרו מגעה ברשות הרבים מהו נישמעינה מן הדא מעוברת ומיניקה טהורות לבעליהן וכן אשה שיש לה ווסת ושאר כל הנשים טהורות בביאה ומטמאות במגע הדא אמרה ודאי מגעה ברשות הרבים טמא. רבי יודן בעי בדקה חלוקה בשחרית ומצתה טהור ובמנחה ומצאת עליו כתם פשיטא חלוקה אינו טמא אלא עד שעת בדיקה גופה מהו שיהא טמא מעת לעת. כלום את מטמא גופה אלא מחמת חלוקה חלוקה אינו טמא אלא עד שעת בדיקה וגופה טמא מעת לעת: והמשמשת בעדים הרי זו כפקידה. היך עבידא בדקה עצמה בשחרית ושימשה בעד בחצות וראת במנחה אין טמא אלא עד שעת תשמיש לוי אמר בעד של אחר התשמיש היא מתניתא אבל בעד שלפני התשמיש המומה היא לביתה ואינה בודקת יפה רבי אבון בשם רבי זעירא בעד שלפני התשמיש היא מתניתא אבל בעד של אחר התשמיש דיהא היא מחמת שכבת זרע:

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.

Jerusalem Talmud Niddah