Tefilah and Birkat Kohanim - Chapter Five

A person who prays must be careful to tend to [the following] eight matters. - The specific laws regarding these eight categories are discussed by the Rambam in the ensuing halachot of this chapter.

[However,] if he is pressured - and unable to carry out any or all of these prerequisites.

confronted by circumstances beyond his control - e.g., ill, as explained by the Rambam in Halachah 2.

or transgresses - i.e., even if one transgresses intentionally.

and does not do one of them, they are not of absolute necessity - i.e., one is not required to repeat the prayer or compensate for its recitation.

In the previous chapter, the Rambam listed five categories which are of absolute necessity for prayer. A person who fails to fulfill any of those requirements must repeat his prayers. These eight categories are לכתחילה (at the outset) necessary for the Amidah, but, do not disqualify the prayer if they were not tended to.

The Lechem Mishneh points out that even Chapter 4 refers to certain actions which were only problematic לכתחילה, such as burping and sneezing. Nevertheless, they are included in that chapter because, from a topical perspective, it is more appropriate to discuss them within the context of the general categories mentioned there.

They are: standing, - See Halachah 2.

facing the Temple, - See Halachah 3.

preparation of his body, - See Halachah 4.

proper clothing, - See Halachah 5.

proper place, - See Halachah 6-8.

control of his voice, - See Halachah 9.

bowing - See Halachot 10-12.

and prostration. - See Halachah 13-15.

Standing: What is implied? [Generally,] one should pray only while standing. - As mentioned in Chapter 1, Halachah 1, prayer is called עבודה - service. Thus, it can be compared to the sacrifices in the Temple which are also referred to by that term. In regard to both these services, Deuteronomy 10:8 states: "...To stand before God and serve Him" (Berachot 30a, Tur, Orach Chayim 98).

Indeed, the term Amidah - (lit. "standing") is used to refer to the Shemoneh Esreh because of this requirement. (See Soferim 16:12.)

[Thus,] a person sitting in a boat or in a carriage, if able to stand, should do so; - However, unlike one riding an animal, he is not obligated to sit if he is able to stand (Lechem Mishneh).

if not, he may sit in his place and pray. - Berachot 30a relates a difference of opinion among the Sages whether it is preferable to recite one's prayers early, before the desired time so that one can stand during Shemoneh Esreh or whether one should set out on a journey in a boat or carriage and pray at the appropriate time even though one will not be able to stand.

From this discussion, we may conclude that, under these circumstances, it is acceptable for one to remain seated during the Shemoneh Esreh if doing so will contribute to one's ability to concentrate.

A person who is ill - and would have to strain to stand

may pray even while lying on his side - Note Hilchot Kri'at Shema 2:2 which relates that one may recite the Shema lying on one's side, but not lying on one's back.

provided he is able to have the proper intention - i.e., One who is ill should pray only when he is able to concentrate. However, if he is unable to concentrate, it is better that he should not pray (Rabbenu Manoach).

Hagahot Maimoniot relates that Rashi was accustomed not to pray when he was ill.

Similarly, one who is thirsty or hungry - to the extent that he cannot concentrate

is considered as one who is ill - and is not required to pray. The commentaries point to the statement of the Jerusalem Talmud (Berachot 5:1) that one in discomfort should not pray as the source for this halachah.

[Therefore,] if he is able to concentrate properly he should pray, and if not he should not pray until he has eaten or drunk. - It is questionable whether this halachah is accepted at present, when, after the fact, prayer with a lesser level of concentration is accepted (Ramah, Orach Chayim 101) and siddurim are commonly available (See ibid. 9:3).

One riding an animal should not descend [from the animal] - even if he has someone to hold his animal, - Berachot 30a mentions opinions which require one to descend in this instance, however, the accepted view is...

Rather, he should sit in his place and pray so his mind will be settled - Even if someone were holding his animal, the person would be preoccupied with worries about his animal and, therefore, would be unable to concentrate on his Amidah.

Facing the Temple: What is implied? A person standing in the Diaspora should face Eretz Yisrael and pray. - Berachot 30a explains that this is derived from King Solomon's prayer at the dedication of the Temple (I Kings 8:48): "...and they will pray to You towards their land."

One standing in Eretz Yisrael should face Jerusalem. - as implied by I Kings 8:44: "...and they will pray to God towards the city that You have chosen" (Berachot, ibid.).

One standing in Jerusalem should face the Temple. - as implied by II Chronicles 6:24 (which gives a slightly different account of Solomon's prayer): "...and they will pray towards this House" (ibid.).

The Talmud (ibid.) also relates:

Rav Avin... said: What is implied by the verse: "Your neck is like the tower of David built with turrets (תלפיות) (Song of Songs 4:4)."? A hill (תל) to which all mouths (פיות) turn."

Thus, the Temple is called תל פיות, the hill to which all mouths turn in prayer.

One standing in the Temple should face the Holy of Holies. - as implied by I Kings 8:35: "...and they will pray towards this place." Berachot (ibid.) concludes: "Thus, all of Israel direct their hearts towards one place." (See also the commentary to Chapter 1, Halachah 3.)

A blind person, one who is - in a new place and is...

unable to determine direction, or one travelling in a boat - who cannot face whatever direction he desires lest he fall

should direct his heart towards the Divine Presence - as implied by I Kings 8:44: "...and they will pray to God" (ibid.).

and pray - In his commentary on the Mishnah (Berachot 4:5), the Rambam explains that one should imagine himself facing the Holy of Holies in the Temple.

The preparation of one's body: What is implied? When one stands in prayer, he should place his feet together side by side. - Berachot 10b quotes Ezekiel 1:7 which describes the angels as standing in the following manner: "And their feet are a straight foot." Therefore, when praying, we place our feet together in order to appear as angels - those expert in praising God.

He should set his eyes downwards as if he is looking at the ground, and his heart upwards as if he is standing in Heaven - Yevamot 105b relates:

Rav Chiya and Rabbi Shimon bar Rebbe were sitting together. One of them opened the conversation and said: One praying should set his eyes downwards, as [I Kings 9:3] states: "And my eyes and my heart were there all the days" (i.e., towards the land of Israel and set downwards because of the presence of the Shechinah).
The other said that one's eyes should be pointed upwards, as [Eichah 3:41] states: "Let us lift up our hearts with our hands [towards God in Heaven]."
Rabbi Yishmael, the son of Rabbi Yossi, came and asked them what they were doing. They answered that they were discussing the Amidah. He [Rabbi Yishmael] said: My father said: One praying should set his eyes downwards and his heart upwards in order to fulfill both of those verses.

His hands should be resting on his heart - Shabbat 10a relates: "Ravvah threw off his cloak, clasped his hands together and prayed like a servant before his master."

with the right hand clasped over the left hand - The right side always represents the notion of lovingkindness; the left side, stern justice. Therefore, we hold our hands such that the right overpowers the left: i.e., lovingkindness overpowers stern judgement.

The right side is given prominence over the left in many other contexts because of this idea. (See the Shulchan Aruch, Orach Chayim 2:4.)

He should stand like a servant before his master, - The Maharal (Netiv Ha'avodah, Chapter 6), in his commentary on Berachot 10b quoted above, explains that placing our hands and feet together is a statement of absolute dependence on God. We demonstrate that we are neither able to move to our desired place, nor to act with our hands as we wish. In this way, we show how we are totally given over to His service, as a servant who has no independent existence of his own.

in fear, awe, and dread. - Berachot 30b bases this on Psalms 2:11: "And you shall serve God in fear."

He should not rest his hands on his hips [during the Amidah] - This appears to be based on Rav Yitzchak Alfasi's interpretation of Berachot 24b. The Hagahot Maimoniot explains that such a position conveys an attitude of irreverance. For similar reasons, it is forbidden to lean on anything during the Amidah.

Proper clothing: What is implied? One should adjust his clothing and make himself neat and presentable before [praying], as [implied by Psalms 29:2]: "They bow to God in resplendent holiness." - Berachot 30b relates that, on the basis of this verse, Rav Yehudah would adjust his clothes before praying.

One should not pray wearing [only] his undershirt - Our translation of אפונדתו is based on the Rambam's commentary to the Mishnah, Berachot 9:5, which defines that term as the undergarment worn to collect perspiration, in order that one's outer garments remain fresh. Others explain that it refers to a money belt.

bareheaded - Soferim 14:15 states that one may not utter God's name with his head uncovered. (See also Shabbat 155b.) "One praying must stand with his feet together and cover his head as one standing before the king" (Zohar, Va'etchanan 260b).

or barefoot - Shabbat 10a relates: "Ravvah bar Rav Huna put on fine shoes and then prayed. He said: 'Prepare to meet your God, Israel' (Amos 4:12)."

The Rambam does not mention the source of these halachot or the verse from Amos. Rather, he cites the verse in Psalms, which may be understood as producing a halachah that is more subjective in nature, dependent on the commonly accepted rules of etiquette.

if it is the custom of the people of that place - However, where it is normal practice to walk barefoot, as in particularly hot climates, it is permissible to pray that way (Kessef Mishneh).

to stand before their most respected people - This introduces a subjective element into these laws. The definition of proper clothing is dependent on local custom, i.e., how people dress when they want to make an impression on the respected people in one's community. See also the Shulchan Aruch, Orach Chayim 91:5.

Both the Mishnah Berurah and Aruch Hashulchan mention this idea in regard to wearing a hat and require one to do so during the Amidah if this is the usual way people present themselves.

with shoes.

In all places - i.e., the following rule in this halachah is in no way dependent on local custom, but applicable in all cases.

one should not hold tefillin in his hand or a Sefer Torah in his arms during the Amidah, since he will worry about them - lest they fall (Rashi, Berachot 23b).

[Similarly,] one should not hold utensils or money in his hand - Berachot (ibid) states: "A knife, money, a plate, and a loaf of bread are like them (i.e., like the Sefer Torah and tefillin)." Rashi explains that in these instances as well, one will fear that they will fall and injure him or become lost or ruined.

Based on Rashi's statements, there are authorities who rule that a person may hold an object which would not present a danger or causes worry if it falls, e.g., a notebook. Rabbenu Yonah, however, forbids the holding of any object except the lulav, which is explicitly mentioned in the Talmud. This is also the position of Terumat Hadeshen. (Even according to the latter view, one may hold a prayerbook.)

Shulchan Aruch HaRav (Orach Chayim 96:1) rules that one may also hold other objects (in line with Rashi's position), but states that the optimum manner of performing the mitzvah is not to hold anything, so that his hands may be clasped together over his heart, as the Rambam mentions in Halachah 4.

However, he may pray holding his lulav on Sukkot, - Sukkah 41b relates that Rav Ashi would pray with his lulav in his hand.

since it is the commandment of the day - Since it is the mitzvah of the day, it is dear to him and caring for it is not considering an encumberance that will disturb one's concentration (Rashi).

If one is carrying a burden of less than four kabbim on his head - This halachah quotes Bava Metzia 105b. See our commentary on Chapter 4, Halachah 6, for the modern equivalent of a kav.

when the time for the Amidah arrives, he should throw it over his shoulder and pray. - i.e., holding a burden of this size will not distrub one's concentration.

If it is larger than four kabbim, - holding it during prayer will be a distraction. Hence,...

he should place it on the ground and then pray.

It is customary for all the Sages and their students to pray only when wrapped in a tallit - Shabbat 10a relates that Rav Kahana would wrap himself in a tallit and pray. Ta'anit 20a also tells of Nakdimon ben Gurion, who when praying in the Holy Temple for rain, "wrapped himself in a tallit and stood to pray."

In Hilchot Tzitzit 3:11, the Rambam writes: "It is a great disgrace for a Torah scholar to pray without being wrapped in his tallit."

Proper place: What is implied? One should stand in a low place - Berachot 10b bases this law on the premise, "there is no loftiness before God, as [Psalms 130:1] states: 'From the depths, I call out to you, God.'”

and turn his face towards the wall - Berachot 5b bases this law on Isaiah 38:2: "And Chizkiyahu turned his face towards the wall and prayed."

In his responsa, the Rambam explains that the intent of this law is that one should not have anything before him that will disrupt his concentration on the Amidah. (See Beit Yosef, Orach Chayim 90)

The Shulchan Aruch and the Ramah (Orach Chayim 90:21) discuss this concept. Among their conclusions are that people do not constitute a separation between a person praying and the wall, nor do small objects less than 10 handbreadths (approximately 80 centimeters) tall.

Also, one should open windows or doors - Berachot 31a states "A person should always pray in a house with windows."

In his responsum, the Rambam mentions that this halachah applies only to a house, as explicitly mentioned in the Talmud and not necessarily to a synagogue. However, the Beit Yosef (ibid.) quotes the Zohar (Vol. II, p. 251a), which requires a synagogue to have 12 windows, which correspond to the 12 seraphim in the Heavenly Court. He also quotes this law in his Shulchan Aruch (Orach Chayim 90:4).

Rashi (Berachot 34b) explains that windows are an aid to concentration, as one looks heavenward and is humbled. Rabbenu Yonah suggests that the light has a calming effect, allowing one to concentrate on his prayers.

that face Jerusalem and pray opposite them, - in keeping with the obligation to face Jerusalem mentioned in Halachah 3.

as [Daniel 6:11] states: "...and he had windows open in his room facing Jerusalem" - The verse concludes: "...and he kneeled on his knees three times a day and prayed."

A person should establish a fixed place where he always prays. - Berachot 6b states: "Anyone who establishes a fixed place for his prayer will be assisted by the God of Abraham." Abraham is mentioned because, as can be inferred from Genesis 19:27, he had a fixed place for prayer.

The Jerusalem Talmud, Berachot 4:4, states that even in a synagogue, a person should have a fixed place for prayer and should not move from place to place.

The Shulchan Aruch, Orach Chayim 90:19 quotes this law. The Magen Avraham adds that within four cubits (approx. six feet) of one's place is also considered acceptable, since it is impossible to be in exactly the same spot at all times. Therefore, a person who finds a colleague sitting in one's place in the synagogue, may pray within four cubits of his place. This is preferable to embarrassing the person sitting in his seat, who might very well be a visitor and not be aware of which seats are occupied by regular congregants.

One should not pray in a destroyed building - This halachah is derived within the context of the following narrative (Berachot 3a):

Rabbi Yossi said: Once I was walking on the road and I entered one of the destroyed buildings of Jerusalem in order to pray. Eliyahu [the Prophet] of blessed memory came and waited for me by the entrance until I had finished praying.
After I finished my prayer, he greeted me: "Peace unto you, Rebbe."
I replied to him: "Peace unto you, Rebbe and teacher."
He asked me: "My son, why did you enter this destroyed building?"
I answered him: "To pray."
He told me: "You should have prayed in the road."

The Talmud mentions that one should never enter a destroyed building on any account. Nevertheless, since the Talmud made this statement regarding Rabbi Yossi's prayer, the Rambam teaches the laws concerning destroyed buildings here in Hilchot Tefillah (Kessef Mishneh).

nor should one pray behind a synagogue unless he turns his face towards the synagogue. - Berachot 6b states: "Anyone praying behind a synagogue is called wicked,... this applies only when he faces away from the synagogue, but if he faces the synagogue there is no problem."

Rashi (in Berachot 6b) states that by facing away from the synagogue when one prays, one appears to deny God who is worshiped within. Therefore, even if facing the synagogue requires one to turn away from Jerusalem, it is desirable.

Tosafot, Eruvin 18b, explains that this refers to a person standing on the side of the door facing away from the synagogue, and thus towards the opposite direction of those worshipping inside. Therefore, he must simply turn the other way and solve the problem. Hagahot Maimoniot suggests that “behind a synagogue” may even refer to standing on the side of the synagogue and looking away.

The Shulchan Aruch (Orach Chayim 90:7) mentions all these possibilities and rules that one should refrain from praying in any of these places.

It is forbidden to sit down next to someone in the midst of the Amidah - Berachot 31b refers to Chanah's prayers for a son and her subsequent remarks to Eli, the priest: "I am the woman who stood here with you" (I Samuel 1:26). This verses indicates that Eli, as well as Chanah, was standing at the time.

Rabbenu Yonah also mentions that this applies only to a person sitting idly, but one studying or reciting the Shema need not worry and may continue to sit.

or to pass in front of him - for walking in front of someone will disrupt that person's concentration.

Rabbenu Yonah (commenting on Berachot 27a) explains that this refers only to "in front of him," but not to the side.

The Magen Avraham (Orach Chayim 102:5) points out that the Zohar (Parshat Chayei Sarah) mentions that passing on the side is also forbidden.
The Shulchan Aruch, Orach Chayim 102:5 mentions a practical application of this halachah:

If one completes his Amidah when a colleague is praying behind him, he is forbidden from taking his three steps [backwards] until the person behind him finishes his Amidah. Were he to [step backwards], he is like one passing before another in the midst of the Amidah. One must be especially careful in this, even if the last one began his Amidah after the first person.

except at a distance of four cubits - which is not likely to distract one's colleague.

One should not stand in a place three or more handbreadths high - A handbreadth is the size of a fist: approximately 8 centimeters according to Shiurei Torah. Based on the principle of lavud, anything lower than three handbreadths is considered to be part of the ground itself.

and pray - Berachot 10b mentions this and the following laws within the context of the requirement to pray in a low place stated in the previous halachah.

[Similarly, he should not pray while standing] on a bed, bench, or chair - The special mention of these objects requires explanation, since presumably, they would be included in the general category of a place three handbreadths or more high. The Beit Yosef (Orach Chayim 90) quotes Rabbi Yitzchak Abuhav as suggesting that it is forbidden to pray while standing on these objects even if they are less than three handbreadths high. Even at this low height, a person may be unable to concentrate out of fear that he might fall.

The Prisha (Orach Chayim 90) maintains that it is unlikely that a person would fear falling from such a low height and offers a different rationale. He explains that these objects constitute a separation between the person and the ground. In the Temple, the sacrificial service could be performed only while one was standing directly on the ground. Therefore, our prayers must be recited in a similar manner.

A raised platform that has a surface area of four cubits by four cubits which is the [minimum] size of a house, - This measure is also significant in regard to the laws of property and the prohibition of transferring from one domain to another on the Sabbath.

is considered like an attic. - i.e., it is considered a space in its own right rather than a raised area within a larger space.

Thus, one is permitted to pray there. - Migdal Oz points out that on the basis of this halachah, the leader of the congregation often stands on a raised platform in the synagogue in order that he be heard by all the congregants.

Similarly, if it is surrounded by walls, even if it is not four cubits by four cubits, - though it lacks the necessary size, its walls cause it to be considered as an independent entity. Hence,...

one may pray there, since its height is not noticeable, because it constitutes an area unto itself. - i.e., because of the walls, no one will worry about falling despite the height.

Craftsmen - who are hired to work for others by the hour or day, in contrast, to a person working on his own time.

working at the top of a tree or on top of a board - In his commentary to the Mishnah, Berachot 2:4, the Rambam explains the meaning of the word נדבך as follows:

The custom of those building a wall of earth (as opposed to bricks or stones) was to set up two large boards of wood and throw the earth in between them. They would pack it tight with wooden tools until it had the shape of a wall, and then tie [the two boards together.] Afterwards, they would remove the boards from the structure they had built...

בראש הנדבך means "on top of the wall at the time that they are packing (the earth) between the boards that are called נדבכים."

or wall when the time of the Amidah arrives must descend in order to pray, - The Mishnah (Berachot 16a) contrasts the Shema which these individuals may recite in their places and prayer, which requires that they descend. The difference is that, in the Shema, intense concentration is only required when reciting the first verse, while the entire Shemoneh Esreh should be recited with such intention. Hence, it is likely that in such precarious positions, the fear of falling will prevent a person from maintaining his concentration for this prolonged period. See also Hilchot Kri'at Shema, Chapter 2, Halachah 4.

and then return to their work. - i.e., though they are hired workers and thus, their time is not their own, nevertheless, they are granted the time to fulfill their fundamental religious obligations in the proper manner. However, after discharging those duties, they must return to work immediately.

If they were at the top of an olive or fig tree, they may pray where they are because of the excessive effort [involved in descending]. - Berachot 16a differentiates between these trees and those of other species. Rashi explains that the danger of falling from these trees is minimal because of their thick branches, and, therefore, one may stand there firmly and pray.

The Rambam, based on the Jerusalem Talmud, Berachot 2:5, explains that the wide branches make the descent problematical, and, therefore, the workers may pray in the trees themselves.

What it is that they pray? If they are working for meals alone they recite three Amidahs of 19 blessings - Berachot (ibid.) arrives at this differentiation based on an apparent contradiction between two beraitot, one stating that workers must recite the entire Amidah, and the other stating that the abridged version is sufficient.

Those working for daily wages are in effect paid by the hour and must use their time for their employer in the fullest manner possible. In contrast, implicit in an agreement to work for meals is that a high rate of productivity is not expected from such a worker. Hence, he is granted greater leniency.

If they are working for wages, they recite "Give us understanding" - i.e., the abridged version of the Amidah, discussed in Chapter 2, Halachot 2-4.

In either case, they do not lead the congregation - nor participate in communal prayer because of the additional time involved. Rashi (Berachot 16a) also agrees that this applies even to one working for meals.

or lift up their hands [to bless the people] - i.e., if the artisan is a Cohen he should not bless the people during the repetition of the Amidah. Rather, he should pray and then return to his work at the earliest possible time.

Control of one's voice: What is implied? A person should not raise his voice during his Amidah - Berachot 31a explains that these laws are derived from the description of Channah's prayer (I Samuel 1:13): "Channah spoke unto her heart, only her lips moved, but her voice was not heard."

nor should he pray silently - i.e., merely contemplating on the words of prayer in his heart. The Jerusalem Talmud, Berachot 4:1, states that the phrase, "only her lips moved," implies that she was speaking, not only thinking to herself.

Rather, he should pronounce the words with his lips, whispering in a tone that he can hear - Sotah 32b relates: "Why did they decree that the Amidah must be whispered? In order that those who have transgressed will not be embarrassed."

Rashi explains that transgressors confess their sins before God during the Amidah, and, therefore, the Sages ruled that the entire Amidah should be recited in a hushed tone so that people would not feel embarrassed to confess.

He should not make his voice audible - The first clause of this halachah implies that one should not raise his voice and speak very loudly during the Amidah. This clause teaches that one should not even speak in a normal tone of voice.

Both of these laws are based on Berachot 24b:

One who makes his voice audible during the Amidah is among those of little faith (i.e., he seems to indicate that it is necessary to speak loudly in order that God should hear him - Rashi).
One who raises his voice in the Amidah is among the false prophets. (Rashi explains that this is based on I Kings 18:28, which describes the actions of the false prophets of Ba'al: "And they called out loudly.")

Lechem Yehudah notes that the mention of both these halachot is somewhat unnecessary. The prohibition of making one's voice audible alone would appear to be sufficient. However, since that prohibition is lifted on occasion as explained below, the Rambam mentioned also the first law which is followed regardless of the circumstances involved.

unless he is sick or cannot concentrate otherwise, - When stating the abovementioned restriction, Berachot (ibid.) mentions that it can be relaxed in this eventuality.

In such a case, it is permitted except when in a congregation, lest the others be disturbed by his voice. - The Shulchan Aruch, Orach Chayim 101 allows an exception to this rule on Rosh Hashanah and Yom Kippur. On these days, people devote more concentration to their prayers. Also, they generally pray from a prayerbook. Therefore, they are less likely to be disturbed by someone else's voice. Nevertheless, the Magen Avraham notes that the Zohar suggests praying in a hushed tone even on these days.

Bowing, - The bows in the Amidah are intended to express the concept of complete abnegation of self (See Tanya, Chapters 39 and 42).

what is implied? One praying bows five times in each and every Amidah: - Berachot 34a relates that a person who bows at any other time should be taught to discontinue his practice.

In the first blessing, at the beginning and at the end - i.e., one bows during the recitation of ברוך אתה at the beginning of the blessing and the recitation of ברוך אתה at the end.

in the blessing of thanks, - The blessing מודים, the second to last blessing of the Amidah.

at the beginning and at the end - i.e., at the recitation of the words מודים אנחנו לך (We are thankful to You) and the recitation of ברוך אתה at the end.

and upon completing the Amidah, one bows and takes three steps backwards - Hagahot Maimoniot points out that one should begin his three steps backwards with his left foot, in order that his right foot be the last to withdraw from before God.

while bowing - Yoma 53b mentions that Rav Chiya, the son of Rav Huna, saw that Ravva and Abbaye took three steps backwards in the midst of a prolonged bow.

He takes leave - Yoma (ibid.) states: "A person who prays must take three steps backwards and then take his leave. Anyone who does not do this is better not to have prayed at all"

from his left and afterwards, from his right - See Halachah 11 for the explanation of this halachah.

When he bows the [other] four times, he does so at [the utterance of the word] "Blessed" and straightens up when [reciting] G‑d's name. - Berachot 12a explains the latter law based on Psalms 146:8: "God straightens those bent over."

The Maharal (Netiv Ha'avodah, Chapter 10) explains that this reflects how God is the source of all life and He grants man the power to act.

Then, he lifts his head up from the bowed position.

To whom does the above apply? To an average person. However, the High Priest bows at the beginning and end of each and every blessing. - The commentaries question the Rambam's statements, noting that there are two opinions concerning this law mentioned in Berachot 34a, b and neither corresponds to the Rambam's text. See Kessef Mishneh.

A king bows at the beginning [of the Amidah] and does not lift his head until he completes his whole Amidah. - Berachot (ibid.) bases this statement on I Kings 8:54: "And so it was when Solomon completed praying to God..., he rose from kneeling before the Altar of God."

Rashi explains that the High Priest and King bow down more because a person who occupies a position of greatness must lower and subjugate himself before God. The Maharal (ibid.) mentions that bowing is a natural response to one's feelings of closeness to God. Therefore, these two men, closer than others to God, bowed more frequently.

Why should one take leave from the left first? - as stated in the previous halachah

Because one's left is to the right [side] - Yoma 53b relates:

One should take leave from the right and then from the left, as [Deuteronomy 33:2] states: "From His right [came] a fiery teaching for them," and [Psalms 91:7] states: "A thousand fall by Your side and ten thousand from Your right."
Ravva saw that Abbaye took leave from his right side first. He said to him: "Do you think this refers to your right? It refers to your left, which is the right side of the Holy One, blessed be He."

The Zohar (II p. 32a) makes similar statements:

Since the Holy Name is on the right and the Torah is on the right, all is dependent on the right. We learn that one must raise up the right over the left, as [Deuteronomy 33:2] states: "From His right [comes] a fiery teaching for them."

of His countenance - Rashi, Yoma (ibid.) explains that during prayer, one must envision himself standing before the Divine Presence. Thus, his right side is actually opposite God's left, so to speak.

i.e., just like when one stands before a - mortal

king, he takes leave from the right of the king, and then afterwards, from the left of the king. Thus, they - The Sages of the Great Assembly, when laying down the rules for prayer,

established that one should withdraw from the Amidah in the same manner as he withdraws from before a king.

All these bows require that one bow until the vertebrae in his spine protrude - Rashi (Berachot 28b) explains that one must bow until a colleague could see the פקקים (joints) in his back. Lechem Yehudah states one must bow until the vertebrae stick out.

and he makes himself like a bow - Berachot (ibid.) states that one should bow until he could see a coin placed opposite his heart. The Rashba explains that this refers to a coin that would be placed on the ground opposite one's heart. Thus, one should not bend over completely, but rather curve his back such that he can see the ground.

However, if one bows slightly [to the extent that] it causes him pain and he appears to have bowed with all of his power, he need not worry. - Berachot (ibid.) states:

Rabbi Chanina says: "One need not do more than nod his head."
Ravva commented: "This is the case if it causes him pain, as long as he appears as one who is bowing."

Prostrating, what is implied]? After one lifts his head from the fifth bow, he sits on the ground, falls with his face towards the earth, and utters all the supplications - Megillah 22b relates that the custom of falling to the earth in supplication was followed in Babylonia in Talmudic times.

The Tur, Orach Chayim 131, explains that the reason for prostrating oneself after Shemoneh Esreh is that by doing so, one prays in all three positions of prayer employed by Moses:

sitting (during the verses of Praise), - "...and I sat on the mountain 40 days and 40 nights" (Deuteronomy 9:9),
standing (during Shemoneh Esreh) - "And I stood on the mountain as on the first day for 40 days and 40 nights" (Deuteronomy 10:10),
prostration - "And I fell down before God, as at first, for 40 days and 40 nights" (Deuteronomy 9:25).

The Zohar (Parshat BaMidbar) explains that after prayer, a person should feel as if he has returned his soul to God and has no life-energy left. Thus, he falls to the ground where he receives new spiritual power.

that he desires - i.e., there is no fixed text of prayers recited at this time. In his Seder Tefilot kol HaShanah, the Rambam writes: "It is our custom to make supplication while prostrated with these statements and verses; sometimes, mentioning them all and sometimes, mentioning only some of them."

Thus, though there was a basic text for these prayers (which is, to a large extent, included in the extended Tachanun recited on Mondays and Thursdays), what a person actually said was still left to his own creative impulse.

There are two different versions of תחנון today. The תחנון of Nusach Ha'ari is based on Psalm 25, whereas that of Nusach Ashkenaz and Nusach Sefard is based on Psalm 6.

"Kneeling" always refers to [falling to] one's knees; - Megillah 22b derives this law from I Kings 8:54: "And so it was when Solomon completed his Prayer to God... that he rose from kneeling on his knees."

"bowing," to bending over on one's face; - This is derived from I Kings 1:31: "And Bat Sheva bowed with her face to the earth" (ibid.).

and "prostration," to stretching out on one's hands and feet until he is lying flat with his face on the ground. - This is derived from Genesis 37:10: "Will it come to pass that I and your mother and brothers will prostrate ourselves to you on the ground" (ibid.).

The definition of these three terms is important within the context of the following halachah.

When uttering the supplication - i.e., the prayer recited after Shemoneh Esreh. In Hebrew, the Rambam uses the term נפילת אפים, which means literally "falling on the face." However, this translation is employed since the intent of "falling on one's face" is to recite these supplications.

after the Amidah, there are those who bow and there are those who prostrate themselves - Megillah 22b indicates that this variance in custom existed even in Talmudic times.

It is interesting that in Halachah 13, the Rambam mentioned only histachavah, prostrating oneself, as the proper method for נפילת אפים. Perhaps, he considered it the most preferable position.

It is forbidden to prostrate oneself on stones except in the Holy Temple, as we have explained in Hilchot Avodat Kochavim - Chapter 6, Halachot 6 and 7. There, the Rambam explains that it was a normal practice of idolators to place stones down in order to prostrate themselves upon them. He states that the Biblical prohibition - (Leviticus 26:1): "You shall not place a paved stone in your land to bow upon it" - refers to השתחואה alone, as opposed to simply bowing, which although forbidden, does not obligate punishment. See also Sefer Hamitzvot, Negative Commandment 12.

The Rambam also notes that prostration was permitted in the Temple, since the above verse mentioned only "your land". Similarly, because of this prohibition, it is customary to lie rugs or mats on top of the stone floors in most synagogues.

An important person is not permitted to fall on his face unless he is certain that he is as righteous as Yehoshua - Megillah (ibid.) relates:

An important person is not permitted to fall on his face unless he will be answered like Yehoshua bin Nun, as [Joshua 7:10] states: "God said to Yehoshua: 'Get up and go. Why is it that you have fallen on your face?'”

Rashi explains that a person of stature would be subjected to ridicule if his prayer were not answered as Yehoshua's was.

The Jerusalem Talmud, Ta'anit 2:6, restricts the application of this Halachah. According to one version, the limitation exists only to יחיד על הציבור (an individual who is praying on behalf of the community). Another version states יחיד בציבור (an individual in a congregation).

In these cases, there might be cause for embarrassment if he was not answered. However, there is no such restriction when an individual prays by himself. See also Tosafot, Megillah (ibid.).

Rather, he should tilt his face slightly, but not press it to the ground. - Megillah (ibid.) derives this law from the actions of Ravvah and Abbaye, who followed this practice instead of falling to the ground in accordance with the above rule.

The Shulchan Aruch (Orach Chayim 131:8) rules in accordance with the Rambam. The Ramah adds that no one should prostrate himself on the floor even if it is not stone. Therefore, the custom today is that everyone rests their heads on their arms while reciting Tachanun.

One may pray in one place and offer this supplication in another place. - The Lechem Mishneh maintains that this can be derived from the following narrative in Megillah (ibid.). Rav came to a synagogue in Babylonia, but did not fall to the ground after the Shemoneh Esreh as they did. One of the explanations offered by the Talmud for his behavior is that there was a stone floor in front of Rav, but not in front of the other congregants. The Talmud then asks: "Why didn't Rav move to their place?", obviously implying that one may offer this supplication in a place other than one's place of prayer.

It is an accepted custom among the entire Jewish people not to utter the supplication on Sabbaths or festivals. Nor [does one utter it] on Rosh Hashanah, Rosh Chodesh, Chanukah or Purim - This custom is also mentioned in the Siddur of Rav Saadia Gaon.

The days mentioned are all joyous occasions. At such times, we do not beseech God with extra supplication. Rather, we concentrate on the goodness that we have already received from Him. Similarly, we refrain from נפילת אפים at other occasions of joy; for example, a bride and groom on the day of their wedding and the week following it, and the participants in a ברית מילה (circumcision) are exempt from נפילת אפים. (See Shulchan Aruch, Orach Chayim╟13 131:4.)

or in Minchah on the eve of Sabbaths or holidays, - when the festive nature of these days can already be felt.

nor in the Evening Prayer of any day - The Beit Yosef (Orach Chayim 131) explains that we refrain from reciting Tachanun at night for mystic reasons. Tachanun relates to the aspect of stern judgement which is also identified with the night. It is not proper to combine both aspects of judgement together.

There are [however,] individuals who do utter the supplication in the Evening Prayer - Otzar Geonim on Megillah 23b discusses the various customs regarding the utterance of נפילת אפים. Rav Sar Shalom mentions that, although it is not his custom, there are some people who do נפילת אפים after מעריב.

On Yom Kippur only, one utters the supplication in every prayer, since it is a day of supplication, requests, and fasting. - Though we recite confessional prayers in each service of Yom Kippur, the only times we fall to the ground in supplication is during the Avodah of the Musaf prayers (Ma'aseh Rokeach).