Halacha

הלכה א
תְּפִלַּת הַצִּבּוּר נִשְׁמַעַת תָּמִיד וַאֲפִלּוּ הָיוּ בָּהֶן חוֹטְאִים אֵין הַקָּדוֹשׁ בָּרוּךְ הוּא מוֹאֵס בִּתְפִלָּתָן שֶׁל רַבִּים. לְפִיכָךְ צָרִיךְ אָדָם לְשַׁתֵּף עַצְמוֹ עִם הַצִּבּוּר. וְלֹא יִתְפַּלֵּל בְּיָחִיד כָּל זְמַן שֶׁיָּכוֹל לְהִתְפַּלֵּל עִם הַצִּבּוּר. וּלְעוֹלָם יַשְׁכִּים אָדָם וְיַעֲרִיב לְבֵית הַכְּנֶסֶת שֶׁאֵין תְּפִלָּתוֹ נִשְׁמַעַת בְּכָל עֵת אֶלָּא בְּבֵית הַכְּנֶסֶת. וְכָל מִי שֶׁיֵּשׁ לוֹ בֵּית הַכְּנֶסֶת בְּעִירוֹ וְאֵינוֹ מִתְפַּלֵּל בּוֹ עִם הַצִּבּוּר נִקְרָא שָׁכֵן רַע:
כסף משנה
1.
Communal prayer is always heard. Even when there are transgressors among [the congregation], the Holy One, blessed be He, does not reject the prayers of the many.1Berachot 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 community2This 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.3i.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.

One should always spend the early morning and evening [hours] in the synagogue, for prayer will not be heard4i.e., accepted by God at all times5The 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.6Berachot 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.7Berachot 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."

הלכה ב
וּמִצְוָה לָרוּץ לְבֵית הַכְּנֶסֶת שֶׁנֶּאֱמַר (הושע ו ג) ״וְנֵדְעָה נִרְדְּפָה לָדַעַת אֶת יְיָ׳‎״. וּכְשֶׁיֵּצֵא מִבֵּית הַכְּנֶסֶת אַל יַפְסִיעַ פְּסִיעָה גַּסָּה אֶלָּא יֵלֵךְ מְעַט מְעַט. וּכְשֶׁיִּכָּנֵס בְּבֵית הַכְּנֶסֶת יִכָּנֵס שִׁעוּר שְׁנֵי פְּתָחִים וְאַחַר כָּךְ יִתְפַּלֵּל לְקַיֵּם מַה שֶּׁנֶּאֱמַר (משלי ח לד) ״לִשְׁמֹר מְזוּזֹת פְּתָחָי״:
כסף משנה
2.
It is a mitzvah to run to the synagogue as [Hoshea 6:3] states: "Let us know. Let us run to know God."1The 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.2Rashi (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,3Rashi (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."4The 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.

הלכה ג
בֵּית הַמִּדְרָשׁ גָּדוֹל מִבֵּית הַכְּנֶסֶת. וַחֲכָמִים גְּדוֹלִים אַף עַל פִּי שֶׁהָיוּ לָהֶם בְּעִירָם בָּתֵּי כְּנֵסִיּוֹת הַרְבֵּה לֹא הָיוּ מִתְפַּלְּלִין אֶלָּא בְּמָקוֹם שֶׁהָיוּ עוֹסְקִין שָׁם בַּתּוֹרָה וְהוּא שֶׁיִּתְפַּלֵּל שָׁם תְּפִלַּת הַצִּבּוּר:
כסף משנה
3.
A study hall is greater1i.e., it is a more auspicious place to pray. than a synagogue.2Other ramifications of this concept are mentioned in Chapter 11, Halachah 14, and in Hilchot Talmud Torah 4:9. 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.3Berachot 30b relates: "Even though there were thirteen synagogues in Tiberias, Rav Ami and Rav Assi would pray only between the pillars in the study hall."
Berachot 8a interprets the phrase "the gates of Zion" in Psalms 87:2: "God loves the gates of Zion above all the dwellings of Jacob" as referring to "the gates of those who are בהלכה המצויינים (distinguished by the halachah studied there)" and states that they receive the highest degree of Divine attention.
The Talmud continues: Abbaye says: "Originally, I would study in my house and pray in the synagogue. After hearing this, I pray only where I study."

The above applies, [however, only] when one can participate in communal prayer there.4The Kessef Mishneh mentions the view of certain rabbinic authorities who maintain that it is preferable for a scholar to pray in a study hall even without a minyan. However, he also mentions the opinion of Rabbenu Asher (See Responsum 4) who writes that if the scholars do not appear in the synagogue the common people will assume that their presence is also unnecessary. The Shulchan Aruch (Orach Chayim 90:18) quotes the Rambam's position.

הלכה ד
וְכֵיצַד הִיא תְּפִלַּת הַצִּבּוּר. יִהְיֶה אֶחָד מִתְפַּלֵּל בְּקוֹל רָם וְהַכּל שׁוֹמְעִים. וְאֵין עוֹשִׂין כֵּן בְּפָחוֹת מֵעֲשָׂרָה גְּדוֹלִים וּבְנֵי חוֹרִין. וּשְׁלִיחַ צִבּוּר אֶחָד מֵהֶם. וַאֲפִלּוּ הָיוּ מִקְצָתָן שֶׁכְּבָר הִתְפַּלְּלוּ וְיָצְאוּ יְדֵי חוֹבָתָן מַשְׁלִימִין לָהֶם לַעֲשָׂרָה. וְהוּא שֶׁיִּהְיוּ רֹב הָעֲשָׂרָה שֶׁלֹּא הִתְפַּלְּלוּ. וְכֵן אֵין אוֹמְרִים קְדֻשָּׁה וְלֹא קוֹרְאִין בַּתּוֹרָה וּמְבָרְכִין לְפָנֶיהָ וּלְאַחֲרֶיהָ וְלֹא מַפְטִירִין בַּנְּבִיאִים אֶלָּא בַּעֲשָׂרָה:
כסף משנה
4.
What is implied by [the term,] communal prayer? One [person] prays aloud and all [the others] listen.1With this statement, the Rambam touches on a point debated both by the Sages of the Talmud and the later Rabbis. The mishnah, Rosh HaShanah 33b, states:
Just as the leader of the congregation is obligated [to pray], each individual is obligated. Rabban Gamliel states: "The leader of the congregation fulfills the obligation on behalf of the community."
The Talmud (34b) elaborates on the difference of opinion:
They asked Rabban Gamliel: "According to your opinion, why does the community pray?"He replied: "In order to allow the leader of the community to prepare his prayers."Rabban Gamliel asked them: "According to your opinion, why does the leader of the congregation pray aloud?"They replied: "In order to allow those who are not knowledgeable to fulfill their obligation."He told them: "Just as he fulfills the obligation on behalf of those who are not knowledgeable, he fulfills it on behalf of those who are knowledgeable."
The Sages of the Talmud continued to debate the issue. The ultimate decision accepted by Rav Yitzchok Alfasi, the Rambam (See Halachah 9), and Rabbenu Asher, is that during the entire year, the Sages' opinion is accepted. However, on Rosh HaShanah, because of the complexity of the blessings (See Halachah 10), Rabban Gamliel's opinion prevails.
Both Rabban Gamliel and the Sages agree that the practice of communal prayer involves two elements:a) the silent prayers of many individuals; andb) the chazan's repetition of the Shemoneh Esreh.They differ, however, as to which of these elements is considered of primary importance. According to the Sages, the essential element of communal prayer is that ten or more people recite the Shemoneh Esreh at the same time. According to Rabban Gamliel, the essential element of communal prayer is, as the Rambam states in this halachah, the prayer of the leader of the congregation.
[Note Likkutei Sichot, Vol. 24, which explains that their difference of opinion revolves around a more general issue: Which is of higher priority, quantity (the prayers of the many) or quality (the prayers of the leader of the congregation)?]
The Rambam's statement here is difficult to place in perspective. Though in Halachah 9, he accepts the Sages' view (See also Chapter 9, Halachot 2-3) in this halachah, his opinion follows that of Rabban Gamliel. In one of his responsa, the Rambam explains that after the Sages instituted the silent Shemoneh Esreh to allow the leader of the congregation to prepare his prayers, even Rabban Gamliel would agree that all the individuals praying in a minyan also fulfill their obligation to pray by reciting their own prayers. Still it is difficult to understand why the Rambam would have the individuals forfeit the higher quality of communal prayer in order to pray individually.
In his notes to Rosh HaShanah, ibid., Rav Chayim Soloveichik writes that to take into consideration the Rambam's statements in this halachah, after concluding his individual prayers, each person should stand and listen to the prayer of the leader of the congregation and thus, fulfill the mitzvah of communal prayer. Note Likkutei Sichot, ibid., which compares answering to the chazan's prayer to reciting a voluntary prayer (See Chapter 1, Halachah 9). By doing so, one will have both the advantages of individual and communal prayer.
This should not be done with fewer than ten2See Halachot 4 and 5. adult3Males who have reached the age of thirteen years and a day and manifested signs of physical maturity. (See Hilchot Kri'at Shema 3:19.)
The Kessef Mishneh explains that the Rambam derives this halachah from Berachot 47b-48a which allows for the inclusion of a child in the zimmun for the grace after meals. (See Hilchot Berachot 5:7.) We assume that this leniency was granted only in regard to grace, but not in regard to prayer. See also Bereishit Rabbah 91:3.
Many Halachic authorities do not accept this conclusion. In his siddur, Rav Sa'adia Gaon rules that a child may be counted as the tenth in a minyan. Similarly, the Ba'al HaMe'or holds that even up to four minors may be counted in a minyan for prayer.
The Shulchan Aruch (Orach Chayim 55:4), rules that a minor may not be included in a minyan for prayer. The Ramah adds that under extraordinary circumstances, a minor may be counted. There are opinions that in such a case, the minor must be at least six years old, understand that prayer is service to God, and hold a chumash (Magen Avraham 55:5, Shulchan Aruch HaRav 55:5).
free males.4i.e., excluding a Canaanite slave. However, a Jewish slave (עבד עברי) may be counted as part of a minyan. Berachot 47b relates that once, Rabbi Eliezer entered the synagogue and finding only nine people there, freed his slave to complete the quorum of ten. The leader of the congregation is [counted as] one of them.5Though there is no explicit source to this effect, a number of midrashim (e.g., VaYikra Rabbah 23:4) lead to this conclusion.
One of the communal rites listed in Megillah 23b which requires a minyan is ברכת אבלים - the blessing one utters to those in mourning. For the recitation of that blessing, the presence of ten men other than the mourner himself is required. (See Hilchot Eivel 13:1.) Perhaps the Rambam feels that this statement is necessary to clearly distinguish between the different requirements of a minyan for prayer and ברכת אבלים.

Even if some of them have already prayed and fulfilled their obligation, they can complete the [quorum of] ten6Though they do not pray together with the others, their presence in the room where the others pray can complete a minyan. provided the majority of the ten have not prayed.7Soferim 10:7 states:Our Sages in the West say [that Kaddish and barchu may be recited] even with seven. They explain their position [based on Judges 5:2]: "In the time of tumult in Israel when the people volunteered themselves, blessed be God." [The number of people correspond] to the number of words [in the verse which describes the blessing of God].There are those who say only six [are required], since ברכו is the sixth word [of the above verse].
The Rambam differentiates between the ruling regarding prayer and his statements in Hilchot Berachot 5:8 where he writes that it is necessary that seven people out of ten eat bread in order to constitute a minyan for zimmun, for "a noticeable majority" is required.
There are two views quoted in the name of Rabbenu Tam (Tosafot, Megillah 23b); one, requiring a minimum of seven people who have not prayed for a minyan just as seven who have eaten bread are required for a minyan in regard to grace after meals and, another, requiring, only five. However, the Rambam's opinion is universally accepted as halachah.
Similarly, we should not recite Kedushah, - See Chapter 7, Halachah 17.
In the chazan's repetition of the Shemoneh Esreh, it is customary to recite three verses in the Kedushah:a) "Holy, Holy, Holy, is the Lord of Hosts; the entire earth is full of His glory" (Isaiah 6:3 ;b) "Blessed be the glory of God from His place" (Ezekiel 3:12 ;c) "The Lord shall reign forever, your God, O Zion, throughout all generations" (Psalms 146:10 .
Only the first two of these verses are recited in the Kedushah of the blessings before the Shema. However, in theKedushah recited at the end of the service, a verse similar to Psalms 146:10 is also included.
The commentaries debate the definition of Kedushah and therefore, question which passage the Rambam requires to be omitted when one prays alone. The Rambam's statements in Chapter 9, Halachah 5, appear to define Kedushah as only the first of these three verses.

Similarly, we should not recite Kedushah, read the Torah with its blessings8i.e., the reading of the Torah as part of the prayer service. Reading from a Torah scroll for the purposes of study does not require a quorum. before and after it,9See Chapter 12, Halachah 3. or read the haftorah from the Prophets except in [a quorum of] ten.10The Mishnah (Megillah 23b) equates the reading of the haftarah with other "holy matters" that require a minyan.

הלכה ה
וְכֵן לֹא יִהְיֶה אֶחָד מְבָרֵךְ בִּרְכַּת שְׁמַע וְהַכּל שׁוֹמְעִים וְעוֹנִין אַחֲרָיו אָמֵן אֶלָּא בַּעֲשָׂרָה. וְזֶה הוּא הַנִּקְרָא פּוֹרֵס עַל שְׁמַע. וְאֵין אוֹמְרִים קַדִּישׁ אֶלָּא בַּעֲשָׂרָה. וְאֵין הַכֹּהֲנִים נוֹשְׂאִים יְדֵיהֶם אֶלָּא בַּעֲשָׂרָה וְהַכֹּהֲנִים מִן הַמִּנְיָן. שֶׁכָּל עֲשָׂרָה מִיִּשְׂרָאֵל הֵם הַנִּקְרָאִים עֵדָה שֶׁנֶּאֱמַר (במדבר יד כז) ״עַד מָתַי לָעֵדָה הָרָעָה הַזֹּאת״ וְגוֹ׳‎ וְהָיוּ עֲשָׂרָה שֶׁהֲרֵי יָצְאוּ יְהוֹשֻׁעַ וְכָלֵב:
כסף משנה
5.
Similarly, one [person] should not recite the blessings1Even though the published text of the Mishneh Torah uses the singular term, "blessing," as will be explained, the plural is more appropriate. The authoritative Oxford and Yemenite manuscripts of the Mishneh Torah also use the plural. 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.2This law is also based on the mishnah in Megillah 23b. Commenting on that mishnah, the Rambam defines פריסה as "presentation," i.e., the public reading of the blessings before the Shema. If people want to fulfill their obligation to recite the blessings associated with the Shema by answering "Amen" to the chazan's blessings instead of reciting those blessings themselves, a quorum of ten is required. See also Chapter 9, Halachah 1.
[Rabbenu Yonah supports this definition of פריסה based on the Targum Yonaton of I Samuel 9:13.]
Rashi, the Ra'avad, and others (See Shulchan Aruch, Orach Chayim 69:1) define פריסה as "dividing in half." They explain the ceremony of poreis al Shema to refer to a situation where ten individuals who have already recited their prayers come together. One individual acts as a chazan and recites Kaddish, Barchu, and the first of the blessings before the Shema.
One only recites Kaddish - Kaddish is recited to mark different stages in the prayer service, after public study, and in memory of the departed.
Note also the brief remarks the Rambam makes concerning this prayer in his Order of Prayers for the Entire Year.

One only recites Kaddish with ten.3Soferim 10:7 also considers Kaddish as a "holy matter" which requires a minyan. The priests do not bless the people4literally, "raise their hands," for the priestly blessing is recited with raised hands. See Leviticus 9:22 and Chapter 14, Halachah 3. except [in the presence of a quorum of] ten. The priests [themselves] may be considered part of the quorum.5See Chapter 15, Halachah 9.
[Ten are required] because6These prayers and rituals are considered "holy matters" which require a congregation (as mentioned in the following halachah) and... every [group of] ten Jews is called a congregation as [implied by Numbers 14:27]: "How long [must I suffer] this evil congregation."7This verse records God's complaint about the spies sent to collect information about Eretz Yisrael (Numbers, Chapters 14 and 15). Twelve spies were sent. They8The spies whom God condemned for trying to persuade the Jews that it was impossible to conquer Eretz Yisrael were ten, for Joshua and Calev9though also sent on the mission were not included [among them].10and, in fact, resisted these attempts, calling for the Jews to enter the land as God had commanded.

הלכה ו
וְכָל דְּבַר קְדֻשָּׁה לֹא יְהֵא אֶלָּא בְּתוֹךְ הָעֵדָה מִיִּשְׂרָאֵל שֶׁנֶּאֱמַר (ויקרא כב לב) ״וְנִקְדַּשְׁתִּי בְּתוֹךְ בְּנֵי יִשְׂרָאֵל״. וְכָל אֵלּוּ הַדְּבָרִים אִם הִתְחִילוּ בָּהֶם בַּעֲשָׂרָה וְהָלְכוּ מִקְצָתָם אַף עַל פִּי שֶׁאֵין רַשָּׁאִין יִגְמְרוּ הַשְּׁאָר:
כסף משנה
6.
Any holy matter1e.g., the prayers and rituals mentioned in Halachot 4 and 5. may only [be performed] in a congregation2i.e., a quorum of ten (see the previous halachah). of Jews, as [Leviticus 22:32] states: "And I shall be sanctified among the children of Israel".3Megillah 23b explains as follows: Leviticus 22:32 states, "And I shall be sanctified among the children of Israel." A גזרה שוה (an analogy based on the use of common words) is made between this verse and Numbers 16:21, "Separate yourselves from among this congregation" and a second גזרה שוה between the latter verse and the verse, Numbers 14:27, quoted in the previous halachah. Extending our use of the principle of גזרה שוה, we conclude that just as in regard to the spies, a congregation meant a minimum of ten people, the same applies in regards to all situations in which God is "sanctified."
Regarding all these matters, if they were begun with ten [people] and some leave4the place of prayer - even though they are not permitted to5The Jerusalem Talmud (Megillah 4:4) states that Isaiah 1:28, "And those that forsake God will be consumed" applies to those that leave in the middle of communal prayer when less than ten men remain. If more than ten are left, although leaving is undesirable, there is no prohibition. - the remainder6of those left in the minyan. A minimum of six people is, nevertheless, required (Shulchan Aruch, Orach Chayim 55:2). should conclude [the holy matter].7In one of his responsa, the Rambam writes that if a congregation began the first blessing before Kri'at Shema with ten people and then some left, leaving less than a minyan, the congregation may continue and recite the Kedushah in that blessing (see Chapter 7, Halachah 17). The chazan may also repeat the Shemoneh Esreh out loud including Kedushah, but he should not recite the Kaddish after Shemoneh Esreh, since it is not part of the "holy matter" started while the minyan was present.
The Shulchan Aruch (Orach Chayim 55:2-3) rules that, in such an instance, though the blessings of Kri'at Shema may be recited without deviating from the normal practice, the Shemoneh Esreh with Kedushah should not be recited. If the repetition of the Shemoneh Esreh was begun with ten, it may be completed including its Kedushah.
The Ramah (ibid.) adds that, in such a case, one even recites Kaddish after ובא לציון גואל since the Kaddish refers to Shemoneh Esreh.

הלכה ז
וְצָרִיךְ לִהְיוֹת כֻּלָּם בְּמָקוֹם אֶחָד וּשְׁלִיחַ צִבּוּר עִמָּהֶם בְּמָקוֹם אֶחָד. חָצֵר קְטַנָּה שֶׁנִּפְרְצָה בִּמְלוֹאָהּ לְחָצֵר גְּדוֹלָה וְהָיוּ תִּשְׁעָה בַּגְּדוֹלָה וְיָחִיד בַּקְּטַנָּה מִצְטָרְפִין. תִּשְׁעָה בַּקְּטַנָּה וְיָחִיד בַּגְּדוֹלָה אֵין מִצְטָרְפִין. צִבּוּר בַּגְּדוֹלָה וּשְׁלִיחַ צִבּוּר בַּקְּטַנָּה יוֹצְאִין יְדֵי חוֹבָתָן. צִבּוּר בַּקְּטַנָּה וּשְׁלִיחַ צִבּוּר בַּגְּדוֹלָה אֵין יוֹצְאִין יְדֵי חוֹבָתָן שֶׁהֲרֵי הוּא מֻפְלָג מֵהֶם וְאֵינוֹ עִמָּהֶם בְּמָקוֹם אֶחָד מִפְּנֵי שֶׁיֵּשׁ בַּגְּדוֹלָה פַּסִּין מִכָּאן וּמִכָּאן הֲרֵי הִיא כְּמוֹ מֻפְלֶגֶת מִן הַקְּטַנָּה וְאֵין הַקְּטַנָּה מֻפְלֶגֶת מִן הַגְּדוֹלָה אֶלָּא הֲרֵי הִיא כְּקֶרֶן זָוִית שֶׁלָּהּ:
כסף משנה
7.
All [ten members of a congregation] and the leader of the congregation must be in one place.1This principle is the basis for the particular laws which follow.
[The following rules apply when] a small courtyard opens up in its entirety into a large courtyard:2This situation is described by the Mishnah, Eruvin 92a. The laws that follow in this and the following halachah are discussed by the Talmud immediately thereafter.
In his Commentary on the Mishnah, the Rambam explains that the small courtyard has only three walls. The fourth side opens into the larger courtyard. The large courtyard has three full sides, with the fourth side consisting of two short walls on each side of the opening into the small one. The accompanying diagram is based on a diagram drawn by the Rambam (accompanying his Commentary on the Mishnah) to depict this situation.micha, drawing
If there are nine [people] in the large one and one in the small one,3since the majority of the people are in the larger courtyard and the smaller courtyard opens up to the larger one in its entirety they may be considered as a4single group5located in the larger courtyard. [to form a quorum of ten].6The same law would apply if four people were in the smaller courtyard. If there are nine [people] in the small one and one in the large one,7Since the majority is in the smaller courtyard they are not considered as a8single group.9located in the smaller courtyard because the walls of the larger courtyard separate it from the smaller one.
If a congregation is in the large one, but the leader of the congregation is in the small one, - he, like the individual(s) mentioned above, is considered part of the group in the larger courtyard. Hence,

If a congregation is in the large one, but the leader of the congregation is in the small one, they10the congregation, can fulfill their obligation.11by listening to his prayers and answering "Amen" as stated in Halachah 9. If the congregation is in the small one, but the leader of the congregation is in the large one,12he, like the individual(s) mentioned above, is not considered part of the group in the smaller courtyard. Hence, they do not fulfill their obligation13by listening to his prayers since he is separate from them and not with them in one place.14since he is separate from them and not with them in one place.
[The motivating principle15i.e., the reason why individuals in the smaller courtyard can be considered as part of a group located in the larger courtyard, but individuals in the larger courtyard cannot be considered as part of a group located in the smaller courtyard, 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.16It follows that if the smaller courtyard has walls on the side that opens to the larger courtyard, the above laws do not apply. By the same token, a person(s) standing in the courtyard of a synagogue or in an adjoining room cannot be considered as part of a minyan.
Nevertheless, the Shulchan Aruch (Orach Chayim 55:14) qualifies this restriction and states that if the person in the outer room can see - and be seen by - the people in the main room, he may be counted together with them. Even if he is merely peering through a window, he is considered as part of that group.
The Shulchan Aruch 55:20 also mentions that even when the people in adjoining rooms cannot see each other, those in the outer room may respond to Kaddish and Kedushah. The rabbis differed as to whether a person praying in a separate room next to the room where a minyan is praying may be considered to have participated in communal prayer or not (See Mishnah Berurah 55:58).

הלכה ח
וְכֵן אִם הָיְתָה צוֹאָה בַּגְּדוֹלָה אָסוּר לְהִתְפַּלֵּל וְלִקְרוֹת קְרִיאַת שְׁמַע בַּקְּטַנָּה. הָיְתָה צוֹאָה בַּקְּטַנָּה מֻתָּר לְהִתְפַּלֵּל וְלִקְרוֹת קְרִיאַת שְׁמַע בַּגְּדוֹלָה אִם לֹא הָיָה שָׁם רֵיחַ רַע מִפְּנֵי שֶׁהִיא מֻפְלֶגֶת מִמֶּנָּה:
כסף משנה
8.
Similarly, if there were feces in the larger [courtyard], it is forbidden to pray1as stated in Chapter 4, Halachot 8-9, or recite the Shema2as stated in Hilchot Kri'at Shema 3:6-15, in the larger courtyard or [even] in the smaller one.3for it is considered as part of the larger courtyard. Thus, one is considered as praying in a place which contains feces. If there were feces in the smaller one,4The recitation of any holy matter is forbidden in the smaller courtyard. Nevertheless, because the larger courtyard is considered a separate place it is permissible to pray and recite the Shema in the larger one5even if the feces are visible; see Hilchot Kri'at Shema 3:10. provided there is not a foul odor6in which case it would be forbidden. See Hilchot Kri'at Shema 3:10. since [the larger courtyard] is set apart7by its walls from [the feces].

הלכה ט
שְׁלִיחַ צִבּוּר מוֹצִיא אֶת הָרַבִּים יְדֵי חוֹבָתָן. כֵּיצַד. בְּשָׁעָה שֶׁהוּא מִתְפַּלֵּל וְהֵם שׁוֹמְעִין וְעוֹנִין אָמֵן אַחַר כָּל בְּרָכָה וּבְרָכָה הֲרֵי הֵן כְּמִתְפַּלְּלִין. בַּמֶּה דְּבָרִים אֲמוּרִים כְּשֶׁאֵינוֹ יוֹדֵעַ לְהִתְפַּלֵּל אֲבָל הַיּוֹדֵעַ אֵינוֹ יוֹצֵא יְדֵי חוֹבָתוֹ אֶלָּא בִּתְפִלַּת עַצְמוֹ:
כסף משנה
9.
The leader of the congregation can fulfill the obligation [of prayer] on behalf of the congregation.
What is implied? When he1the leader of the congregation, the chazan prays2recites the Shemoneh Esreh (and according to the Rambam - see Halachah 5 - the blessings before the Shema) aloud and they listen3while standing in the posture for prayer and respond "Amen" after each and every blessing, it is considered as if they prayed [themselves].4If one desires to fulfill his obligation with the chazan's prayer, he should answer "Amen," but he should not answer Baruch Hu, uvaruch shemo after the mention of God's name.
To whom does this apply? To one who does not know how to pray.5This follows the opinion of the Sages in the difference of opinion between them and Rabban Gamliel (Rosh HaShanah 33b, 34b) as explained in Halachah 2. However, one who does know how to pray, only fulfills his obligation by praying himself.6Since the essence of prayer is the request for Divine Mercy, it is fitting that each person request for himself (Tosafot Yom Tov, Rosh HaShanah).
See also the opening halachot of Chapter 9 which deal with the practical application of the concepts mentioned in this halachah.

הלכה י
בַּמֶּה דְּבָרִים אֲמוּרִים בִּשְׁאָר יְמוֹת הַשָּׁנָה חוּץ מֵרֹאשׁ הַשָּׁנָה וְיוֹם הַכִּפּוּרִים שֶׁל שְׁנַת הַיּוֹבֵל. אֲבָל בִּשְׁנֵי יָמִים אֵלּוּ שְׁלִיחַ צִבּוּר מוֹצִיא אֶת הַיּוֹדֵעַ כְּשֵׁם שֶׁמּוֹצִיא מִי שֶׁאֵינוֹ יוֹדֵעַ מִפְּנֵי שֶׁהֵם בְּרָכוֹת אֲרֻכּוֹת וְאֵין רֹב הַיּוֹדְעִים אוֹתָן יְכוֹלִין לְכַוֵּן דַּעְתָּן כִּשְׁלִיחַ צִבּוּר. לְפִיכָךְ אִם רָצָה הַיּוֹדֵעַ לִסְמֹךְ בִּשְׁנֵי יָמִים אֵלּוּ עַל תְּפִלַּת שַׁ״ץ לְהוֹצִיאוֹ יְדֵי חוֹבָתוֹ הָרְשׁוּת בְּיָדוֹ:
כסף משנה
10.
When does the above apply? Throughout the entire year with the exception of Rosh HaShanah, and Yom Kippur of the Jubilee year.1specifically, in contrast to the yearly Yom Kippur services.
Even on Sabbaths and festivals when the prayers differ from those recited every day, a person who knows how to pray is expected to pray alone. However, note one of the Rambam's responsa which states that, on Sabbaths and festivals, rather than begin with silent prayer, the chazan should begin by reciting the Shemoneh Esreh out loud together with Kedushah. Those who do not know how to pray should listen to his prayers with the intention of fulfilling their obligation. Those who know how to pray should recite their prayers, word by word, together with the chazan.

On these two2Though we celebrate Rosh HaShanah as two days by Rabbinic decree, the Torah itself requires only one day to be celebrated. days,3All the Rabbis agree that although the halachah follows the Sages throughout the entire year, on these two days, an exception is made and Rabban Gamliel's opinion prevails. the leader of the congregation can fulfill the obligation [of prayer]4In particular, this refers only to the musaf 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]5This leniency is granted because [the Shemoneh Esreh recited on these days contains] long blessings6See Chapter 2, Halachah 6, and in greater detail, Hilchot Shofar 3:8-9. There, the Rambam explains that, on these days, one is required to recite three extra blessings:Malchuyut - which expresses the theme of God's sovereignty,Zichronot - which describes God's remembrance of His love for the Jews, andShofrot - which praises the shofar as a means of manifesting the previous two concepts.
Each of these three blessings includes the recitation of ten verses that express these themes: four from the Torah, three from the prophets, and three from Psalms.
In Chapter 2, Halachah 8, the Rambam writes that on Yom Kippur of the Jubilee year, one recites exactly the same blessings as on Rosh HaShanah.
and most people do not know them [to the extent] that they can have the same intention as the leader of the congregation.7Here, the Rambam does not appear to interpret "intention" as referring to the chazan's concentration and spiritual awareness, but simply, to his familiarity with the text of the blessings.
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.8Though in principle, this ruling is accepted by all authorities, in practice, Ashkenazic Rabbis have advised each person to pray individually even on Rosh HaShanah since, at present, the use of machzorim which include a full text of the blessings is widespread. Furthermore, the inclusion of piyyutim (liturgical poems) in the chazan's repetition of the Shemoneh Esreh makes it very difficult to fulfill one's obligation by listening to his prayer and reciting "Amen." See Shulchan Aruch HaRav 591:1-4.

הלכה יא
אֵין מְמַנִּין שְׁלִיחַ צִבּוּר אֶלָּא גָּדוֹל שֶׁבַּצִּבּוּר בְּחָכְמָתוֹ וּבְמַעֲשָׂיו. וְאִם הָיָה זָקֵן הֲרֵי זֶה מְשֻׁבָּח בְּיוֹתֵר. וּמִשְׁתַּדְּלִין לִהְיוֹת שְׁלִיחַ צִבּוּר אָדָם שֶׁקּוֹלוֹ עָרֵב וְרָגִיל לִקְרוֹת. וּמִי שֶׁלֹּא נִתְמַלֵּא זְקָנוֹ אַף עַל פִּי שֶׁהוּא חָכָם גָּדוֹל לֹא יְהֵא שַׁ״ץ מִפְּנֵי כְּבוֹד צִבּוּר. אֲבָל פּוֹרֵס הוּא עַל שְׁמַע מִשֶּׁיָּבִיא שְׁתֵּי שְׂעָרוֹת אַחַר שְׁלֹשׁ עֶשְׂרֵה שָׁנִים:
כסף משנה
11.
Only a person of great stature within the community in both wisdom1Torah knowledge and deed2performance of the mitzvot; alternatively, deeds of kindness, so that his appointment will be appreciated by all members of the community. should be appointed3The Lechem Mishneh mentions that this applies only to the appointment of a permanent chazan and does not apply to someone who leads the congregation in prayer on occasion. The Shulchan Aruch (Orach Chayim 53:6) mentions this in regard to a chazan having a full beard. as the leader of the congregation.4Ta'anit 16a interprets Jeremiah 12:8: "She raises his voice against Me, therefore, I (God) have hated her" as a reference to a chazan who is unfit for this responsibility.
Most of the commentaries point to the mishnah (Ta'anit 2:2) as the source for the Rambam's statements. Though that mishnah deals with the appointment of the leader of communal prayer for a public fast, there is no reason to assume that the same principles should not apply to the appointment of a chazan at other times. In the Talmud (e.g., Rosh HaShanah 32a), we find many examples of leading Sages serving as chazanim.
If he is an older man,5Though the Hebrew, זקן, is often used to connote a wise man (See Hilchot Talmud Torah 6:1), this translation has been chosen based on the later statements of this halachah. it is very praiseworthy. An effort should be made6i.e. it is desirable, but not an absolute requirement. to appoint as the leader of the congregation, someone who has a pleasant voice7so that listening to his prayers will be enjoyable.
Throughout the generations, in their responsa, our Rabbis have chided the people for putting a pleasant voice at the top of their priorities for a chazan. [Note the Ramah (Orach Chayim 53:5) who states that it is preferable to appoint a boy of thirteen who understands his prayers as chazan rather than an older man with a pleasant voice who does not know what he is saying. See also Shulchan Aruch (ibid., 53:11).]
In particular, this applies regarding the High Holiday services. These days of sincere prayer should not be turned into concerts of ritual music. Instead, attempts should be made to find a chazan who can truly serve as a spiritual leader. If he also has a pleasant voice, it is obviously more desirable.
and is familiar with reading [Biblical verses].8so that he will not err in his recitation of the prayers.
A person who does not have a full beard9The Rabbis have explained that this simply refers to a person of intermediate age. Therefore, in one of his responsa, the Rambam states that a person who is physically incapable of growing a beard may serve as chazan and the requirement of a beard is only mentioned as a sign of "a full state of knowledge which one [usually] reaches at the age when one's beard begins to grow." See also Shulchan Aruch (ibid. 53:8).
However, a beard is also considered a sign of commitment to Jewish practice. The Rambam (Hilchot Avodat Kochavim 12:7) associates shaving with the practices of gentile priests. Many Rabbis have strongly encouraged growing a beard even when there is no question of violating the prohibition against shaving. (See Sefer Mitzvot Gadol 7, Shibolei Leket Vol. II, 41.)
However, in communities where removing one's facial hair in a permitted manner is an accepted practice, the lack of a beard is not considered as a deterrent against a person serving as a chazan.
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.10The Shulchan Aruch (ibid.:6) states that this only refers to the appointment of a permanent chazan. However, Rabbenu Nissim interprets the Rambam's words as meaning that even on occasion, a youth should not serve as a chazan. See also Chapter 15, Halachah 4. However, he may recite the Shema publicly11haporeis al Shema as described in Halachah 5. See Megillah 24a. after he has reached the age of thirteen and manifested signs of physical maturity.12until then, he is a minor and incapable of fulfilling the obligation of prayer on behalf of an adult.

הלכה יב
וְכֵן הָעִלֵּג כְּגוֹן מִי שֶׁקּוֹרֵא לְאָלֶ״ף עַיִ״ן אוֹ לְעַיִ״ן אָלֶ״ף וְכָל מִי שֶׁאֵינוֹ יָכוֹל לְהוֹצִיא אֶת הָאוֹתִיּוֹת כְּתִקּוּנָן אֵין מְמַנִּין אוֹתוֹ שְׁלִיחַ צִבּוּר. וְהָרַב מְמַנֶּה אֶחָד מִתַּלְמִידָיו לְהִתְפַּלֵּל לְפָנָיו בְּצִבּוּר. הַסּוּמָא פּוֹרֵס עַל שְׁמַע וְנַעֲשֶׂה שְׁלִיחַ צִבּוּר. אֲבָל מִי שֶׁכְּתֵפָיו מְגֻלּוֹת אַף עַל פִּי שֶׁהוּא פּוֹרֵס עַל שְׁמַע אֵינוֹ נַעֲשֶׂה שְׁלִיחַ צִבּוּר לִתְפִלָּה עַד שֶׁיִּהְיֶה עָטוּף:
כסף משנה
12.
Similarly, the inarticulate who pronounce an alef as an ayin or an ayin as an alef1Megillah 24b relates that a chazan should not be appointed from Beit Shean or Haifa, since they mispronounce these letters. Rashi explains that such mispronunciations will cause blessings to be read as curses. For example, if the word, יאר, the first word of the second priestly blessing, פניו אליך ‘ה יאר, is read with an ע instead of an א, it becomes a curse. or one who cannot articulate the letters in the proper manner should not be appointed as the leader of a congregation.2For many Jews today, this halachah is rather difficult to observe since we do not differentiate between the pronunciation of an alef and an ayin or a sin and a samech. The Radbaz and the Pri Chadash write that if these pronunciation errors are commonplace, even someone who pronounces a chet as a hay or a shin as a sin may serve as a chazan. See Shulchan Aruch HaRav 53:16, Mishnah Berurah 53:37-38.
The Mishnah Berurah also cites Chapter 15, Halachah 1, from which it appears that a person who stutters, lisps, or has another speech defect which prevents him from pronouncing the letters properly should not serve as a chazan.
A teacher may appoint one of his students to lead the prayers in his presence. - even if the student lacks the above qualities (Kessef Mishneh). Though the previous halachah stated that the leader of the congregation should be the man of the greatest stature in the community, the mishnah (Megillah, ibid.) and similarly, several sources throughout the Talmud (See Berachot 33b) indicate that a teacher could appoint a student to serve as a chazan instead of doing so himself.
The Or Sameach explains that this refers to a student who does not articulate the letters properly. Though such a person should not ordinarily serve as a chazan, if he is appointed by his teacher he may. Thus, we find that Rabbi Yehudah HaNasi appointed Rabbi Chiya as a chazan (Bava Metzia 85b) even though he would pronounce a chet as a hay (Megillah 24b).

A teacher may appoint one of his students to lead the prayers in his presence. A blind person may recite the Shema publicly3even though the first blessing before the Shema thanks God for creating light, a blind person also benefits from light (Megillah ibid.). and serve as the leader of a congregation.4Perhaps the Rambam thought it necessary to clarify this point because there was a difference of opinion among the Sages as to whether a blind person is obligated in all the mitzvot or not. The Sages concluded that he is obligated. Hence, he can also fulfill the obligations of others as the leader of the congregation. A person whose shoulders are uncovered5though he may recite the Shema publicly - may not serve as the leader of the congregation until he is covered by a cloak. - Soferim 14:15 understands this as a gesture of respect for the congregation. See also Rosh HaShanah 17b which states that when God taught Moses the thirteen attributes of mercy, "He robed himself as a chazan."
This does not necessarily refer to wearing a tallit gadol, but rather to a cloak or jacket that covers his shoulders and arms (Shulchan Aruch, Orach Chayim 53:13). However, in many communities, it is customary for a chazan to wear a tallit as a token of respect for the community.
- though he may recite the Shema publicly - may not serve as the leader of the congregation until he is covered by a cloak.

אהבה הלכות תפילה וברכת כהנים פרק ח
Ahavah Tefilah and Birkas Kohanim Chapter 8