Where to pray its appropriateness

THE QUORUM OF 10
PROOFTEXTS THE NECESSITY OF PUBLIC PRAYER FROM RAMBAM
Commentary Halacha 1
Communal prayer is always heard - Berachot 7b-8a relates: the importance of an auspicious time
http://www.chabad.org/dailystudy/rambam.asp?tDate=3/26/2012&rambamChapters=3

Rav Yitzchok asked Rav Nachman: "Why did you not come pray in the synagogue?"
[Rav Nachman] answered him: "I was unable to."
He said: "Gather ten men together and pray."
He responded: "The matter is a bother to me."
[Rav Yitzchok] suggested: "Tell the leader of the congregation to let you know when it is the time for prayer."
He said: Why is all this trouble necessary?"
He replied: "Rabbi Yochanan said in the name of Rabbi Shimon bar Yochai: What is [the meaning of Psalms 69:14] 'As for me, let my prayer be to You, God, at an auspicious time'? When is an auspicious time? The time when the congregation is praying."

The Talmud continues, mentioning other prooftexts which emphasize the importance of praying together with a minyan.

Even when there are transgressors among [the congregation], - Eichah Rabbah explains this concept with the following parable. A group of people fashioned a crown for a king. Among them was a poor person who also put something of his own into the crown. Though the king noticed the poor man's contribution, since the crown as a whole found favor in his eyes, he accepted it and put it on his head. The Midrash continues: By the same token, if there are ten righteous people praying and one evildoer stands among them, will God say: Because of the evildoer, I will not accept their prayers?

Menachot 27a even attributes a positive dimension to the presence of the wicked in communal prayer:

[There are] four species in the [mitzvah of] lulav; two of which (the lulav and the etrog) bear fruit (refer to the righteous, Rashi) and two of which (the myrtle and the willow) do not bear fruit (refer to the wicked, ibid.).
The species which bear fruit require the presence of those which don't and the species which don't bear fruit require the presence of those that do. A person does not fulfill his obligation until he has all of them in one bound unit.
So, too, the Jewish people, when they seek acceptance [from God], must be one bound unit.

Accordingly, on Yom Kippur, it is customary to invite sinners to join in the prayer service. Note also the conclusion of Iggeret HaShmad where the Rambam encourages tolerance and acceptance toward sinners who come to the synagogue to pray.

[Note also the Sh'loh who writes that the word, צבור - "community" - is an acronym for the words, צדיקים - "the righteous," בינונים - "the intermediates," and רשעים, "the wicked."]

the Holy One, blessed be He, does not reject the prayers of the many. - Berachot 8a cites Psalms 55:19: "He delivered my soul in peace from the battle against me, for there were many who strove with me," as the prooftext for this concept.

Therefore, a person should include himself in the community - This phrase is quoted - somewhat out of context - from Berachot 29b-30a which explains why we recite our prayers in the plural. The Rambam borrows the concept and uses it to summarize the above teachings and derive the following directive.

and should not pray alone whenever he is able to pray with the community. - i.e., though praying without a minyan is permissible, one should do so only when he has no other alternative.

One should always spend the early morning and evening [hours] in the synagogue - i.e., one should be found in the synagogue at the times of the three Daily Prayers; Shacharit in the morning, Minchah in the late afternoon and Maariv at night.

The Rambam uses the word ישכים - to rise early. Perhaps he is alluding to Berachot 47b which states:

One should always rise early and go to the synagogue in order to merit being counted among the first ten present. Even if 100 people come after him, he receives the reward of all of them.

Alternatively, perhaps he is referring to his statement, Hilchot Kri'at Shema 1:11, that one should recite the Shema before sunrise.

for prayer will not be heard - i.e., accepted by God

at all times - The Lechem Mishneh explains: Prayer which is recited with the proper intentions outside the synagogue may be accepted, but there is no guarantee that prayer will be accepted at all times...

except [when recited] in the synagogue. - Berachot 6a derives this concept from I Kings 8:28: "...to listen to the song and the prayer." "In the place of song (i.e., the synagogue where the people sing God's praises - Rashi), prayer should be [recited]."

The Kessef Mishneh adds that based on this concept, one should pray in the synagogue even when he is praying alone. The Kessef Mishneh also rules that if one is unable to go to the synagogue he should, at least, attempt to pray at the same time as the community. He quotes both these concepts in his Shulchan Aruch, Orach Chayim 90:9.

Though this and the following two halachot mention the importance of a synagogue, the synagogue is discussed here only within the context of the importance of communal prayer. In Chapter 11, the Rambam focuses on the sanctity of the synagogue as a subject in its own right.

Anyone who has a synagogue in his city and does not pray [together] with the congregation in it is called a bad neighbor. - Berachot 8a derives this concept based on Jeremiah 12:14: "So says God regarding all my evil neighbors that touch the inheritance (i.e., the synagogues and houses of study) that I have bequeathed to My people Israel."

When quoting this law, the Shulchan Aruch (Orach Chayim 90:11) also quotes the continuation of the above Talmudic passage:

Furthermore, they cause dispersion to themselves and their children as [the verse in Jeremiah continues]: "Behold, I will uproot them from their land."
HALACAH 2 COMMENTARY
Commentary Halacha 2
http://www.chabad.org/dailystudy/rambam.asp?tDate=3/26/2012&rambamChapters=3

It is a mitzvah to run to the synagogue as [Hoshea 6:3] states: "Let us know. Let us run to know God." - The Tur (Orach Chayim 90) adds that it is also a mitzvah to run to perform other commandments.

A person should not take long steps when he leaves the synagogue. Instead, he should proceed [slowly,] step by step. - Rashi (Berachot 6b) explains that hurrying away from the synagogue, suggests that one views the synagogue and the obligations contained therein to be a burden.

When one enters a synagogue he should go in the distance of two doorways and then pray, - Rashi (Berachot 8a) explains that we are obligated to enter the distance of two doorways widthwise in order not to appear anxious to leave. The Beit Yosef (Orach Chayim 90) explains that this refers to a distance of eight handbreadths.

The Hagahot Maimoniot interprets the Talmud's statement, "the measure of two doorways" as a matter of time, not distance. One should wait a few moments after entering the synagogue before he starts to pray.

The Hagahot Maimoniot also states that according to the interpretation that the "measure of two doorways" refers to actual distance, this requirement only applies when the synagogue is located near the public thoroughfare. If it is not, one may pray near the door. Rabbenu Yonah also mentions that a person whose fixed place for prayer in the synagogue is beside the door does not violate this requirement. It is obvious that he is sitting there not because of his desire to leave quickly, but because it is his seat in the synagogue.

[in order] to fulfill [the instructions of Proverbs 8:34] which states: "to guard the posts of My doors." - The Jerusalem Talmud (Berachot 5:1) points to the plural forms of "posts" and "doors" as indicating the need to enter the distance of two doorways.


Halacha 3
A study hall is greater than a synagogue. Even though [some of the] great Sages [lived in] cities where many synagogues were located, they would pray only in the place where they studied Torah.

The above applies, [however, only] when one can participate in communal prayer there.

Halacha 4
What is implied by [the term,] communal prayer? One [person] prays aloud and all [the others] listen. This should not be done with fewer than ten adult free males. The leader of the congregation is [counted as] one of them.

Even if some of them have already prayed and fulfilled their obligation, they can complete the [quorum of] ten provided the majority of the ten have not prayed.

Similarly, we should not recite Kedushah, read the Torah with its blessings before and after it, or read the haftorah from the Prophets except in [a quorum of] ten.
Halacha 5
Similarly, one [person] should not recite the blessings associated with the Shema while the others listen and answer "Amen" except [in the presence of a quorum of] ten. This is called poreis al Shema.

One only recites Kaddish with ten. The priests do not bless the people except [in the presence of a quorum of] ten. The priests [themselves] may be considered part of the quorum.

[Ten are required] because every [group of] ten Jews is called a congregation as [implied by Numbers 14:27]: "How long [must I suffer] this evil congregation." They were ten, for Joshua and Calev were not included [among them].

Halacha 6
Any holy matter may only [be performed] in a congregation of Jews, as [Leviticus 22:32] states: "And I shall be sanctified among the children of Israel".

Regarding all these matters, if they were begun with ten [people] and some leave - even though they are not permitted to - the remainder should conclude [the holy matter].

Halacha 7
All [ten members of a congregation] and the leader of the congregation must be in one place.

[The following rules apply when] a small courtyard opens up in its entirety into a large courtyard: If there are nine [people] in the large one and one in the small one, they may be considered as a group [to form a quorum of ten]. If there are nine [people] in the small one and one in the large one, they are not considered as a group.

If a congregation is in the large one, but the leader of the congregation is in the small one, they fulfill their obligation. If the congregation is in the small one, but the leader of the congregation is in the large one, they do not fulfill their obligation since he is separate from them and not with them in one place.

[The motivating principle is] that the walls on each side of the large courtyard separate it from the small one. [However], the smaller one is not separated from the large one, but rather, is considered as its corner.

Halacha 9
The leader of the congregation can fulfill the obligation [of prayer] on behalf of the congregation.

What is implied? When he prays and they listen and respond "Amen" after each and every blessing, it is considered as if they prayed [themselves].

To whom does this apply? To one who does not know how to pray. However, one who does know how to pray, only fulfills his obligation by praying himself.

Halacha 10
When does the above apply? Throughout the entire year with the exception of Rosh HaShanah, and Yom Kippur of the Jubilee year.

On these two days, the leader of the congregation can fulfill the obligation [of prayer] on behalf of those who know [how to pray] just as he can fulfill the obligation [of prayer] on behalf of those who do not know [how to pray] because [the Shemoneh Esreh recited on these days contains] long blessings and most people do not know them [to the extent] that they can have the same intention as the leader of the congregation.

Therefore, on these two days, even a person who knows [how to pray] is granted permission to rely on the prayers of the leader of the congregation to fulfill his obligation [of prayer] if he so desires.

Halacha 11
Only a person of great stature within the community in both wisdom and deed should be appointed as the leader of the congregation. If he is an older man, it is very praiseworthy. An effort should be made to appoint as the leader of the congregation, someone who has a pleasant voice and is familiar with reading [Biblical verses].

A person who does not have a full beard should not be appointed as the leader of the congregation even if he be a wise man of great stature, as a gesture of respect to the congregation. However, he may recite the Shema publicly after he has reached the age of thirteen and manifested signs of physical maturity
Halacha 12
Similarly, the inarticulate who pronounce an alef as an ayin or an ayin as an alef or one who cannot articulate the letters in the proper manner should not be appointed as the leader of a congregation.

A teacher may appoint one of his students to lead the prayers in his presence. A blind person may recite the Shema publicly and serve as the leader of a congregation. A person whose shoulders are uncovered - though he may recite the Shema publicly - may not serve as the leader of the congregation until he is covered by a cloak.