Rav Achai arranged that his son should marry a daughter of R. Yitzchak bar Shmuel; his son was unable to consummate the marriage. Rav Achai went to investigate why; he found a Sefer Torah in the room.

Rav Achai: You endangered my son!

(Beraisa): Relations are forbidden in a house with a Sefer Torah or Tefilin, unless it is removed (from the room) or in a Kli b'Soch Kli (enclosed in two vessels).

(Abaye): Vessels in which it is normally kept cannot be used (for both); even if it is in ten such vessels, they are considered like only one.

(Rava): A cloak over a chest containing Sifrei Torah is like Kli b'Soch Kli (the cloak is not normally used for them).

(R. Yehoshua ben Levi): One must make a partition ten Tefachim tall in front of a Sefer Torah to permit relations [in the room].

Mar Zutra saw a ten Tefachim partition in front of a Sefer Torah in the room of Mar bar Rav Ashi.

Mar Zutra (to Rav Ashi): Do you hold like R. Yehoshua ben Levi? He only permits this if no other house is available -- you have another house!

(Rav Ashi): I did not think about this.

(Mishnah): [To say Shema,] one must distance himself four Amos from urine and excrement.

(Rava): This suffices only if it is in back of him; if it is in front of him, he must distance himself as far as he can see.

The same applies to prayer.

Question: But Rafram bar Papa taught that one may pray facing a Beis ha'Kisei!

Answer #1: That is when there is no excrement inside.

Objection: But Rav Yosef taught that [the Isur to pray near] a Beis ha'Kisei is even if there is no excrement inside, [the Isur to think about Torah in] a bathhouse is even if no one is inside!

Answer #2: Rather, Rafram permits praying facing a Beis ha'Kisei that was not used yet.

Question: But Ravina never resolved whether or not designation for a Beis ha'Kisei takes effect (to make it like a Beis ha'Kisei)!

Answer: His was unsure whether or not it is forbidden to pray inside it, but surely it is permitted to pray facing it.

(Persian latrines are sloped, so the excrement slides down to a place far from the person.)

(Rava): Even if there is excrement in a Persian latrine, it is considered sealed (and thus one may say Shema there).

(Mishnah): The following must immerse (before saying Divrei Torah): a Zav who saw Keri (had a seminal emission), a Nidah who discharged semen, and a woman who became Nidah after relations;

R. Yehudah exempts.

(Gemara) Question: If a Ba'al Keri saw Zivah, does R. Yehudah require him to immerse?

Perhaps R. Yehudah exempts only regarding a Zav who saw Keri, for the decree did not apply to him when he first became Tamei (and now immersion will not be Metaher him), but a Ba'al Keri who sees Zivah must immerse, for the decree applied to him from the beginning of his Tum'ah;

Or, perhaps he does not distinguish.

Suggestion: Perhaps he exempts even a regular Ba'al Keri, and the Mishnah discusses a Zav to teach the extremity of Chachamim's opinion!

Answer (Mishnah): A woman who became Nidah after relations must immerse; R. Yehudah exempts.

She is like a Ba'al Keri who sees Zivah (the decree applied to her from the beginning of her Tum'ah, and R. Yehudah exempts)!

(R. Chiya - Beraisa): If a Ba'al Keri sees Zivah, he must immerse;

R. Yehudah exempts.

(Mishnah): One may pray Shacharis until Chatzos (midday);

R. Yehudah says, he may pray until four hours of the day. (Each hour is 1/12th of the length of the day. The authorities dispute whether the day is measured from dawn until nightfall (Tzeis ha'Kochavim), or from sunrise until sunset.)

One may pray Minchah until evening;

R. Yehudah allows until Plag ha'Minchah (this will be explained).

Ma'ariv is not Kavu'a (fixed; this will be explained);

The time for Musaf is the entire day.

(R. Yehudah says, it is until seven hours of the day -- some delete this from the text.)

(Gemara) Contradiction (Beraisa): The time (for Keri'as Shema) is [to finish] at sunrise, in order to mention Ge'ulah immediately before Shemoneh Esreh and pray during the day.

Answer: That refers to Vatikim.

(R. Yochanan): Vatikin finish the morning Shema at sunrise.

Question: In our Mishnah, no one permits Shacharis after Chatzos;

But Rav Mari said in the name of R. Yochanan that if one mistakenly omitted Ma'ariv, he prays Shacharis twice; if one mistakenly omitted Shacharis, he prays Minchah twice!

Answer: It is permitted to pray the entire day;

Before Chatzos, one is rewarded for praying in the proper time; after Chatzos, one gets reward for praying, but not for praying in the proper time. (Shitah Mekubetzes - alternatively, we could have answered that the law is different when one forgot to pray.)

Question: If one mistakenly omitted Minchah, does he pray Ma'ariv twice?

If one omitted Ma'ariv, he prays Shacharis twice -- but that is because the Tashlumim (compensation) is during the same (Halachic) day -- "va'Yehi Erev va'Yehi Voker Yom Echad" (here, the Tashlumim would be the next day);

Tefilos are in place of Korbanos -- if a Korban (with a fixed time) was not brought that day, there is no Tashlumim!

Or, since Tefilah is a request for mercy, one may pray at any time!

Answer (Rav Huna bar Yehudah citing R. Yochanan): If one mistakenly omitted Minchah, he prays Ma'ariv twice; we do not equate this to a Korban, which may not be offered on a later day.

Question (Beraisa): "Me'uvas Lo Yuchal Liskon" -- this refers to one who missed Keri'as Shema of the evening or morning, or Ma'ariv or Shacharis;

(This explicitly opposes Rav Mari's teaching, and since one may not pray Tashlumim on the same day, all the more so there is no Tashlumim for Minchah the next day!)

"V'Chisaron Lo Yuchal Lehimanos" -- this is one who did not join his friends in doing a Mitzvah.

Answer (R. Yitzchak): The Beraisa discusses one who intentionally omitted praying. (It teaches that even Ma'ariv and Shacharis, which have Tashlumim on the same day (if they were omitted unintentionally), have no Tashlumim if omitted willfully.)

Support (Rav Ashi): The Beraisa says "omitted," it does not say "mistakenly."

(Beraisa #1): If one mistakenly omitted Minchah on Erev Shabbos, he prays twice (Gra - Ma'ariv of Shabbos) on Shabbos night;

If one mistakenly omitted Minchah on Shabbos, he prays two weekday Shemoneh Esrehs on Motza'i Shabbos;

He says Havdalah in [the fourth Berachah of] the first Shemoneh Esreh, not of the second.

If he said Havdalah in the second and not in the first, he was Yotzei the second Tefilah, not the first.

Inference: Since he did not say Havdalah in the first, it is as if he did not say the first Shemoneh Esreh.

Contradiction (Beraisa #2): If (in winter) one mistakenly omitted the mention of rain in the second Berachah or the request for rain in the ninth, he must repeat them (he returns to that Berachah, or, sometimes, he must start again from the beginning of Shemoneh Esreh);

If he mistakenly omitted Havdalah in the fourth Berachah, he does not go back, for he can say Havdalah later with wine.

(Likewise, in Beraisa #1 the first Tefilah should be valid, for he can say Havdalah later!)

This is left difficult. (Rif, cited in Tosfos - we could answer that when he said Havdalah only in the second Shemoneh Esreh, this shows that he intended the first to be Tashlumim and the second for Ma'ariv; Tashlumim must be said only after the current obligation, therefore it was invalid.)

(R. Yosi b'Rebbi Chanina): The Avos enacted the [three daily] Tefilos;

(R. Yehoshua ben Levi): The Tefilos correspond to the Temidim (fixed daily Korbanos).

Each of them is supported by a Beraisa.

Support (for R. Yosi b'Rebbi Chanina - Beraisa #1): Avraham enacted Shacharis -- "va'Yashkem Avraham ba'Boker El ha'Makom Asher Amad Sham"; "Amidah" refers to Tefilah.

Yitzchak enacted Minchah -- "va'Yetzei Yitzchak la'Su'ach ba'Sadeh"; "Sichah" refers to Tefilah.

Yakov enacted Ma'ariv -- "va'Yifga ba'Makom va'Yalen Sham"; "Pegi'ah" refers to Tefilah.

Support (for R. Yehoshua ben Levi - Beraisa #2): One may pray Shacharis until Chatzos, because the morning Tamid may be offered until then;

R. Yehudah says, he may pray until four hours, this is the latest time for the morning Tamid.

One may pray Minchah until evening, the latest time for the afternoon Tamid;

R. Yehudah permits [only] until Plag ha'Minchah, the latest time for the afternoon Tamid (Pesachim 58a). (However, the afternoon Tamid was slaughtered at eight and a half hours of the day, Hakravah was completed at nine and a half hours -- this is the beginning of Minchah Katanah, not Plag ha'Minchah! Tosfos explains that R. Yehudah refers to the time when the Ketores is offered, for it says "Tikon Tefilasi Ketores Lefanecha.")

Question: Why is there no fixed time for Ma'ariv?

Answer: This is because limbs (of Olos) and fats that were not consumed on the Mizbe'ach may be offered the entire night.

Question: Why is the time for Musaf the entire day?

Answer: This is because the Korban Musaf may be offered the entire day.

R. Yehudah permits until seven hours of the day, the latest time for Musafim.

Minchah Gedolah (the earliest time that one may pray Minchah) begins at six and a half hours of the day (the earliest time to offer the afternoon Tamid);

Minchah Katanah (many Rishonim consider this the earliest l'Chatchilah time for Minchah) begins at nine and a half hours of the day (the normal time for the afternoon Tamid).

Question: Does R. Yehudah (who permits until Plag ha'Minchah) refer to the first half (of the time that Chachamim allow for Minchah), or the second half?

Answer (Beraisa #3 - R. Yehudah): One may pray until the latter Plag ha'Minchah, i.e. ten and three quarters hours.

Suggestion: Beraisa #2 refutes R. Yosi b'Rebbi Chanina (Tzelach - Beraisa #1 need not support R. Yosi b'Rebbi Chanina, it does not say that the Avos enacted Tefilos for future generations; Melo ha'Ro'im - he cannot explain what the Tana'im argue about)!

Answer: Indeed, the Avos enacted the Tefilos, Chachamim associated them with Korbanos.

Support: Surely, R. Yosi b'Rebbi Chanina says that Tefilas Musaf corresponds to Korbanos -- none of the Avos enacted it!