1. A person who prayed without concentrating [on his prayers] must pray a second time with concentration. However, if he had concentrated during the first blessing, nothing more is necessary.

A person who errs in the recitation of the first three blessings [of the Shemoneh Esreh] must return to the beginning [of the Shemoneh Esreh]. Should one err in the recitation of the final three blessings, one should return to [the blessing, R'tzey]. If one errs in the midst of [one of] the intermediate blessings, one should return to the beginning of that blessing and [then] conclude one's prayers in the [proper] order.

Should the leader of the congregation err when he is praying out loud, he should [correct himself] based on these principles.

2. However, if the leader of the congregation errs while he is praying in a hushed tone, I maintain that he does not repeat his prayers a second time, because of the difficulty it will cause the congregation. Rather, he relies on the prayer which he will recite out loud.

The above applies when he does not err in the first three blessings. If he errs in their [recitation], he always repeats [his prayers] in the same manner as any [other] individual.

3. Should the leader of a congregation err [in his repetition of the Shemoneh Esreh], become confused and not know where to begin [again] - if he waits for a prolonged period, another person should replace him.

If he errs in the recitation of the blessing [that curses] the heretics, we do not wait for him [to correct himself]; rather, another person should replace him. This applies only when he did not begin this [blessing]. However, if he did begin [the blessing], we wait for him.

The second person should not refuse at this time.

4. From which point should [the substitute for the leader of the congregation] begin? If the first one erred in one of the intermediate blessings, [the substitute] should begin from the beginning of the blessing in which he erred. However, if he erred in one of the first three blessings, the [substitute] starts from the beginning [of the Shemoneh Esreh. If he erred in one of the final [three] blessings, the substitute should begin from [the blessing, R'tzey].

5. A person who says, "I will not lead the congregation in prayer because [I am wearing] colored clothes," should not lead the congregation in that prayer service even when wearing white clothes. If he said, "I will not lead the congregation because I am wearing sandals," he should not lead the congregation even when barefoot.

6. A person who is in doubt whether he prayed or not should not repeat his prayers, unless he recites the second prayer with the intention that it is a voluntary prayer, since an individual may recite voluntary prayers throughout the entire day.

A person who remembers that he has already prayed while he is in the midst of the Shemoneh Esreh should cease [praying] immediately, even if he is in the midst of a blessing. [However,] if he was reciting the evening service, he need not cease [praying], for even at the outset, he did not begin that prayer service with the thought that it was an obligation.

7. A person who erred and recited a weekday prayer on the Sabbath does not fulfill his obligation. If he recalled while he was in the midst of the Shemoneh Esreh, he should conclude the blessing which he has begun and [continue] reciting the Sabbath prayers.

When does the above apply? In the evening, morning, and Minchah services. However, in the Musaf service, one should cease [praying] even in the midst of a blessing. Similarly, if one completed a weekday Shemoneh Esreh with the intention that it be one's Musaf prayers, one must recite Musaf again. This applies on the Sabbath, on a festival, and on Rosh Chodesh.

8. [When] one errs during the rainy season and does not recite either morid hageshem or morid hatal, he must return to the beginning of the prayers. However, if he mentions dew, he need not repeat [his prayers].

Should one err in the summer and recite morid hageshem, he must return to the beginning of the prayers. However, if he omits mention of dew [in the summer], he need not repeat his prayers, for dew is never held back, nor is there a need to request it.

9. [The following rules apply when] one forgets to request rain in the blessing for material prosperity: If he remembers before [the blessing,] shome'a tefilah, he should request rain in [that blessing]. If he [recalls] after reciting the blessing, shome'a tefilah, he should return to the blessing for material prosperity. If he does not recall until after he completes the Shemoneh Esreh, he must return to the beginning of the prayer and pray a second time.

10. [The following rules apply when] a person errs and fails to mention Ya'aleh v'yavo: If he remembers before he has concluded the Shemoneh Esreh, he should return to [the blessing, R'tzey], and recite it. If he remembers after he has concluded his prayers, he must repeat the Shemoneh Esreh from the beginning. If he is accustomed to recite supplicatory prayers after Shemoneh Esreh and remembers after he has concluded his prayers, but before he has lifted up his feet [to step backwards after prayer], he should return to [the blessing, R'tzey].

11. When does the above apply? On Chol Hamo'ed or in the morning or Minchah services of Rosh Chodesh. However, in the evening service of Rosh Chodesh, if one failed to mention it one need not repeat his prayers.

12. In every case in which an individual is required to repeat his prayers [because of an error], the leader of the congregation is also required to repeat his prayers if he made a similar mistake while praying out loud, with the exception of the morning service of Rosh Chodesh.

[In this instance,] if the leader of the congregation failed to mention Ya'aleh v'yavo before completing his prayers, he is not required to repeat his prayers because of the difficulty it would cause the congregation. The Musaf service is still to be recited and Rosh Chodesh will be mentioned there.

13. If during the ten days between Rosh Hashanah and Yom Kippur, one erred and concluded the third blessing, Ha'El hakadosh, he should return to the beginning of the Shemoneh Esreh.

If he erred and concluded the eleventh blessing, Melech ohev tzedakah umishpat, he should return to the beginning of the blessing and conclude Hamelech hamishpat, and continue reciting his prayers in order. If he did not remember until he concluded his prayers, he must recite [his prayers again] from the beginning.

[These laws apply] to both an individual and to the leader of the congregation.

14. If a person erred and did not mention Havdalah in the blessing, chonen hada'at, he should conclude his prayers, without returning [to correct himself]. Similarly, one who did not mention Al hanisim on Chanukah or Purim, or Anenu in the prayers on a fast day, need not repeat his prayers. [These laws apply] to both an individual and the leader of a congregation.

If one remembers before lifting his feet [to step backwards after prayer], he should say: "Answer us because You are the one who hears prayer, redeems, and rescues in all times of difficulty and distress. May the words of my mouth...."

15. [A person who] forgot to recite the afternoon service on the Sabbath eve should recite the Sabbath evening service twice. [The same law applies] on a festival.

[A person who] forgot to recite the afternoon service on the Sabbath or a festival should recite the weekday evening service twice after their conclusion.

He should recite Havdalah in the first of these prayers and not in the second. However, if he recited Havdalah in both prayers or omitted it in both prayers, he fulfills his obligation. Nevertheless, if he did not recite Havdalah in his first Shemoneh Esreh, but mentioned it in his second, he [must] return and recite a third Shemoneh Esreh, since his first prayers were not acceptable because they were recited before the evening service.

Whoever recites two prayers [in succession] - even the morning service and the Musaf service - should not recite them one immediately after the other. Rather, he should wait between prayers, so that his mind will be settled.

16. It is forbidden for a person who is praying with a congregation to pray before the congregation.

[The following rules apply when] a person enters a synagogue and finds the congregation praying in a hushed tone: If he could begin and complete his prayers before the leader of the congregation reached Kedushah, he should recite the Shemoneh Esreh. If not, he should wait until the leader of the congregation begins reciting the Shemoneh Esreh out loud, and pray together with him word for word until the leader of the congregation reaches Kedushah. He should respond to Kedushah with the rest of the congregation and then recite the remainder of the Shemoneh Esreh alone.

One who began reciting the Shemoneh Esreh before the leader of the congregation, [but was unable to conclude his prayers before] the leader of the congregation reached Kedushah, should not interrupt his prayers [to] respond to Kedushah with [the congregation]. Similarly, one should not respond Amen, yehei shemeih rabba mevarach... while in the midst of Shemoneh Esreh. Needless to say, [this applies regarding responding "Amen"] to other blessings.