ONE WHO NEEDS TO MOVE HIS BOWELS MAY NOT PRAY
If one needed to move his bowels, and prayed, was it valid?
Me'iri: It was valid only if he could have delayed defecating for the time to walk a Parsah (about four kilometers; the primary opinion says that this is 72 minutes). This does not apply to one who needed to urinate. If he did not need when he began praying, and the need arose while praying, some say that he does not return to the beginning.
Rav Elyashiv citing Drishah: The Shi'ur of a Parsah is based on Chasidim, who spent an hour in Tefilah, an hours beforehand and an hour afterwards. Really, any amount suffices before and after; Chachamim allotted six minutes before and after, so in all it is 72. R. Akiva Eiger (OC 92a) asks, why did they say that the Shi'ur is a Parsah, and not '72 minutes'? It is to teach that he must be able to delay while walking a Parsah; it is not enough to that he could delay 72 minutes while staying in his place.
Rav Elyashiv: Rashi and the Rif hold that if he can delay this time, he may pray l'Chatchilah. Most Rishonim hold that even in this case, he may not pray; the Shi'ur affects only whether or not his Tefilah was valid. Tzlach asked, according to Rashi, why did R. Shmuel need to teach that he may not pray? Since his Tefilah was To'evah, surely it was forbidden to pray! He answers that the Chidush is, even if he will lose Zman Tefilah. One might have thought that the Shi'ur is only for early Chasidim [who spent an hour in Tefilah]. Alternatively, 'do not pray' is only to begin praying, but if he began b'Heter, he finishes, even if he cannot delay a Parsah.
Rav Elyashiv: According to Rashi, why do we learn from "Hikon" (prepare)? The Shi'ur distinguishes valid Tefilah from To'evah - it is not a mere preparation! The Rosh holds that if he could delay a Parsah, l'Chatchilah he may not pray, unless he will lose Zman Tefilah. This is like praying with a belt and hat - one should not forfeit Zman Tefilah for them. Rashi can say that Hikon teaches about need to urinate. If he cannot delay a Parsah, he may not pray, but if he did, it was valid.
In Shabbos (10a), we learn from "Hikon Likras Elokecha Yisrael" that one should dress honorably when praying!
Maharsha: Both of these are included in "Hikon" (prepare).
WHEN IS IT IMPROPER TO BRING A KORBAN?
How does "Shemor Raglecha [Ka'asher Telech El Beis ha'Elokim]" teach to guard yourself from sinning?
Rashi: Do not sin, lest your feet need to go to the Mikdash to bring a Korban Chatas.
Rif (on the Ein Yakov): It did not say Stam to guard your feet, rather, when you go to Beis ha'Elokim. Therefore, he expounds, when you go anywhere, first go to Beis ha'Elokim to learn Torah and Mitzvos. This will guard your feet from going in the path of evildoers. This is like Rava expounds after this, do not be like fools, who sin and bring a Korban, but do not know if they bring for good... (b) Question: Shmuel told Sha'ul oppositely - Hash-m does not desire Olos and Zevachim, rather, that people heed Him! And so Rashi explained in Koheles!
Maharsha: The Seifa is difficult according to this Perush - "Ki Einam Yod'im La'asos Ra." Since they bring a Korban for their sin, they know it! Therefore, Rava explains that even when a Kesil brings a Korban, he does not bring a Chatas to repent, rather, a Zevach, which is not for his sin.
Does a Korban without repenting help at all?
Iyun Yakov: No, for "Zevach Resha'im To'evah." Also Teshuvah alone does not suffice. Therefore, nowadays that we do not have Korbanos, one must engage in Parashas Korbanos - u'Neshalem Parim Sefaseinu.
What is the significance of "Einam Yod'im La'asos Ra"?
Daf Al ha'Daf citing She'eris Nasan: They do not know how to fix [their] evil. Asiyah is like "v'Asesah Es Tziporneha" (Devarim 21:12) - Tikun (fixing), she cuts them. "Asher Bara Elokim La'asos" is extra - it teaches that Hash-m created so that man will fix (perfect). Bereishis Rabah (11:6) says that everything that Hash-m created in the six days of creation, it needs Asiyah - wheat must be ground... (The Ari Zal learns from "La'asos" that in the future, Hash-m will create new worlds for Tzadikim to be in when He will destroy this world.)
Why does it say 'they do not know if they bring for good or for evil'?
Etz Yosef citing Mayan ha'Brachos: Fools think that the Mitzvah of Korbanos is like other Mitzvos that Hash-m desires. They do not regret their sins. They think that their sins were a path to good, to fulfill the Mitzvah of bringing Korbanos. Really, the purpose of a Korban is that the one who offers thinks that the flaying and dissection should have been done to him due to the magnitude of his sin, for not heeding Hash-m's word. He will accept on himself, if I sinned, I will not add to it. One who brings a Chatas should intend to be careful not to bring another, unlike other Mitzvos, in which one anticipates doing it again.
What is the meaning of 'guard your Nekavim'?
Rashi: Guard Raglecha (what is between your feet), like "Lehasech Es Raglav" (Shmuel I, 24:3). Guard your opening (anus) from passing wind.
Etz Yosef citing Mayan ha'Berachos: Mekubalim say that the Satan can harm a person with stray thoughts at the time of Tefilah only if he gives strength opposite it, i.e. his body is not clean. Therefore, he should defecate and then pray.