R. Shimon asked if anything needs to be fixed; they told him about a place of Safek Tum'ah, it was a burden for Kohanim to go around it.

R. Shimon: Does anyone here know if this place was once Tahor (if so, it is not a cemetery, we may use it

An elder: Here, R. Yochanan ben Zakai (a Kohen) cut lupines (legumes) of Terumah (the place is Tahor).

Version #1 (Tosfos): R. Shimon also made a Tikun (like Yakov. He spread a wet sheet; where the ground was soft, it absorbed water from the sheet.) The soft places he marked Tamei (they were dug), the hard places he marked Tahor.

Version #2 (Rashi): He also cut [and cast down] lupines of Terumah - miraculously, the Tum'ah came to the surface (Chachmas Mano'ach - it moved, causing the dirt above it to soften, showing where is Tamei, so R. Shimon would not Metamei the Terumah), enabling him to mark off the place of Tum'ah.) (end of Version #2)

The elder: R. Shimon just declared the cemetery to be Tahor!

R. Shimon: Had you not been with us (in the matter of demarcating the Tum'ah), or had you been with us but did not agree with us, you could dissent - but you were with us and agreed with us! If you dissent people will say that harlots adorn one another, all the more so Chachamim! (Anaf Yosef - they adorn each other, even though they compete with each other, for the more harlots the more lust in the world - all the more so regarding Kedushah, assent among Chachamim increases dearness of Torah and Yir'as Shamayim! Chasam Sofer - in spite of the competition and mutual hatred, harlots adorn one another in order to be adorned - people will say that Chachamim are craftier, all the more so they honor each other (hoping to receive honor in return, i.e. that is why you initially agreed), and when one sees another succeed, he rebels! Ben Yehoyada - in spite of the hatred, harlots adorn one another to prevent a cheapening of the profession - likewise, you should not belittle Chachamim, this belittles yourself!)

R. Shimon put his eyes on him - the elder died.

R. Shimon went out and saw Yehudah ben Gerim (who had repeated R. Shimon's words, leading to the decree), and was amazed that he was still alive - he put his eyes on him, and turned him into a pile of bones.

(Mishnah): A man must say three things in his house shortly before dark [on Erev Shabbos] - Have you tithed? Have you made an Eiruv? Light Ner Shabbos!

If it is Safek dark (i.e. Safek night), one may not tithe Vadai (definite) Tevel, immerse Kelim, or light Ner Shabbos;

[At this time] one may tithe Demai (Safek Tevel), make an Eiruv, and do Hatmanah (wrap food to keep it warm).

(Gemara) Question: What is the source that one must say command to light Ner Shabbos?

Answer (R. Yehoshua ben Levi): "V'Yodata Ki Shalom Oholecha u'Fokadta Navcha v'Lo Secheta" (you should verify that Ner Shabbos, which promotes Shalom, is lit).

(Rabah bar bar Chanah): Even though one must say these, he should say them gently, in order that people will hearken.

(Rav Ashi): I know this from reasoning even before I heard Rabah's teaching!

Question (Mishnah): One must say three things shortly before dark;

Inference: When it is Safek dark, all are forbidden (one of them is to make an Eiruv).

Contradiction (Seifa): When it is Safek night, one may make an Eiruv.

Answer (R. Aba): One may not make Eiruv Techumim at this time, one may make Eiruv Chatzeros. (On Shabbos one must stay within his Techum, i.e. 2000 Amos in every direction from his residence or city; one can fix his residence anywhere inside his Techum, to allow walking 2000 Amos from there, by leaving an Eiruv (food) there for all of Bein ha'Shemashos. Mid'Rabanan, one may not carry from one Reshus ha'Yachid to a different one, unless Eiruv Chatzeros (food jointly owned by the residents of the Reshuyos) was left.)

(Rava): If Reuven and Shimon each told Levi 'Make an Eiruv (Tosfos - Techumim; Rashi - Chatzeros) for me', and Levi made Reuven's Eiruv before Shabbos and Shimon's Eiruv Bein ha'Shemashos, [even] if Reuven's Eiruv was eaten Bein ha'Shemashos and Shimon's was eaten after dark, both of them are valid.

Question: Either way you say, this is difficult!

If Bein ha'Shemashos is day, Reuven's Eiruv should be invalid; if it is night, Shimon's Eiruv should be invalid!

Answer: [It is Safek day, Safek night -] the law of Eiruv is mid'Rabanan, we are lenient about a Safek.

(Rava): After dark, Hatmanah is forbidden [even] in something that does not add heat - this is a decree lest one heat the food before wrapping it.

Question (Abaye): If so, it should be forbidden even Bein ha'Shemashos!

Answer (Rava): We are not concerned for this, for normally pots are already boiling Bein ha'Shemashos.

(Rava): Hatmanah is forbidden in something that adds heat, even before Shabbos - this is a decree lest one wrap in hot ashes and coals.

Question (Abaye): Before Shabbos this is permitted!

Answer (Rava): We decree lest he will stoke the coals after dark.

(Beraisa): We are unsure if part of Bein ha'Shemashos is day and part is night, or if all of it is day, or if all of it is night - therefore, we are stringent, perhaps it spans two days (this will be explained).

Question: When is Bein ha'Shemashos? (The Gemara will discuss whether we ask about its beginning or its duration.)

Answer #1 (R. Yehudah): It is after sundown, as long as Penei Mizrach (simply translated, the eastern sky) is reddish; when the horizon darkens but not the middle of the sky, it is Bein ha'Shemashos (the Gemara will ask about this); when the middle of the sky is as dark as the horizon, it is night;

Answer #2 (R. Nechemyah): It lasts the amount of time needed to walk [1000 Amos, i.e.] half a Mil (nine or 11 minutes) after sunset - after this, it is night;

Answer #3 (R. Yosi): It lasts as long as the blink of an eye (a moment), immediately after it comes, it is night - one cannot know the exact moment.

(Beraisa): We are stringent, perhaps it spans two days.

Question: What difference does it make if it spans two days?

Answer (Rav Huna brei d'Rav Yehoshua): This affects Tum'ah:

(Mishnah): If a man saw [emissions of Zivah] during Bein ha'Shemashos on two consecutive days (e.g. Sunday and Monday), he is in doubt regarding Tum'ah and Korban. (If the sightings were separated by a day, i.e. he saw Sunday during the day and Monday night; he is not a Zav, he is just a Ba'al Keri; in any other case, the sightings were on the same or consecutive days, he is a Zav; if the sightings spanned all three days, e.g. Sunday's sighting was partially during the day and partially at night, and Monday's sighting was at night, he must bring a Korban.)

If he saw during one Bein ha'Shemashos, he is a Safek Zav (if the sighting was partially during the day and partially at night, he is a Zav; if not, he is just a Ba'al Keri).

Question: [R. Yehudah said that] Bein ha'Shemashos is from sundown, as long as the eastern sky is reddish - this implies that once the horizon darkens, it is night;

But then he says that when the horizon is dark but not the middle of the sky, it is Bein ha'Shemashos!

Answer #1 (Rabah): It means, Bein ha'Shemashos begins at sundown and lasts as long as Penei Mizrach is reddish - when the horizon is dark but not the middle of the sky, this is also Bein ha'Shemashos;

When the middle of the sky is as dark as the horizon, it is night.

Answer #2 (Rav Yosef): After sundown, as long as Penei Mizrach is reddish, it is still day; when the horizon is dark but not the middle of the sky, this is also Bein ha'Shemashos; when the middle of the sky is as dark as the horizon, it is night.

This is consistent with their argument regarding the duration of Bein ha'Shemashos (Rabah holds that it is longer than Rav Yosef says).

Question: How long does Bein ha'Shemashos last?

Answer #1 (Rabah): It is the time to walk three parts of a Mil.

Question: What does this mean?

Answer #1: It means, three half-Milim (3000 Amos).

Rejection: If so, he would have said one and a half Milim!

Answer #2: It means, three thirds of a Mil.

Rejection: If so, he would have said one Mil!

Answer #3: It means, three quarters of a Mil.

Answer #2 (Rav Yosef): It is the time to walk two parts of a Mil.

Question: What does this mean?

Answer #1: It means, two halves.

Rejection: If so, he would have said one Mil!

Answer #2: It means, two quarters of a Mil.

Rejection: If so, he would have said half a Mil!

Answer #3: It means, two thirds of a Mil.

Question: How much do the opinions of Rabah and Rav Yosef differ by?

Answer: They argue about a 12th of a Mil.