(1) It is a positive mitzvah ordained by the Rabbis to read the Megillah at the appointed time. It is well-known that this was ordained by the Prophets.
Everyone is obligated in this reading: men, women, converts, and freed slaves. Children should also be trained to read it. Even the priests should neglect their service in the Temple and come to hear the reading of the Megillah.
Similarly, Torah study should be neglected to hear the reading of the Megillah. Surely, this applies to the other mitzvot of the Torah: the observance of all of them is superseded by the reading of the Megillah. There is nothing that takes priority over the reading of the Megillah except the burial of a meit mitzvah - a corpse that has no one to take care of it. A person who encounters such a corpse should bury it and then read the Megillah.

(2) One can fulfill one's obligation by reading or by listening to another person's reading, provided one listens to a person who is obligated to hear the reading. For this reason, if the reader was a minor or mentally incompetent, one who hears his reading does not fulfill his obligation.

(3) It is a mitzvah to read the entire Megillah and to read it both at night and during the day. The entire night is an appropriate time for the night reading, and the entire day is appropriate for the day reading.
Before the reading at night, one should recite three blessings. They are:

Blessed are You, God, our Lord, King of the universe, who has sanctified us with His commandments and commanded us to read the Megillah.
Blessed are You, God, our Lord, King of the universe, who wrought miracles for our ancestors in previous days at this season.
Blessed are You, God, our Lord, King of the universe, who has granted us life, sustained us, and enabled us to reach this occasion.

During the day, one should not recite the final blessing.
In places where it is customary to recite a blessing after the reading, the following blessing should be recited:

Blessed are You, God, our Lord, King of the universe, who wages our battles and executes judgment on our behalf, who avenges the vengeance wrought against us, who exacts retribution from our enemies on our behalf, and who acquits justly all our mortal enemies. Blessed are You, God, the Almighty, who exacts payment on behalf of His nation Israel from all their oppressors, the God of salvation.

(4) What is the appropriate time for the Megillah to be read? The Sages ordained many different times for its reading, as implied by Esther 9:31: "To confirm these days of Purim in their appointed times." The following are the days on which the Megillah is read:
Every city, whether in Eretz Yisrael or in the diaspora, that was surrounded by a wall at the time of Joshua bin Nun should read the Megillah on the fifteenth of Adar. This applies even when a wall does not surround the city at present. Such a city is called a כרך.
Every city that was not surrounded by a wall at the time of Joshua bin Nun should read the Megillah on the fourteenth of Adar. This applies even when there is a wall surrounding the city at present. Such a city is called an עיר.

(5) In the capital of Shushan, the Megillah is read on the fifteenth of Adar although it was not surrounded by a wall at the time of Joshua bin Nun, because the miracle occurred within it and at that time, the Jews celebrated on that day, as Esther 9:18 states, "And they rested on the fifteenth."
Why was the matter made dependent on the time of Joshua bin Nun? To give honor to the cities of Eretz Yisrael that were in ruin at the time of the Purim miracle. Although they are in ruin at present, this would allow them to read the Megillah on the fifteenth as do the inhabitants of Shushan, since they were surrounded by a wall at the time of Joshua. Thus the commemoration of the miracle would include a remembrance of Eretz Yisrael.

(6) The Sages ordained that the inhabitants of the villages who gather in the synagogues only on Mondays and Thursdays could read the Megillah earlier, on the day when they gather in the synagogues.
What is implied? If the fourteenth of Adar falls on either Monday or Thursday, the Megillah is read on that day. If it falls on a day other than Monday or Thursday, we read on an earlier date, on the Monday or Thursday that is closest to the fourteenth of Adar.

(7) What is implied? If the fourteenth of Adar falls on Sunday, the Megillah is read on the previous Thursday, the eleventh of Adar. If the fourteenth falls on Tuesday, the Megillah is read earlier, on Monday, the thirteenth. If the fourteenth falls on Wednesday, the Megillah is read earlier, on Monday, the twelfth.
Whenever license is granted to read the Megillah before the fourteenth, it should not be read unless ten are present.

(8) In a village where the Jews do not gather together to read the Torah on Mondays and Thursdays, the Megillah should be read only on the fourteenth of Adar. When a city does not have ten people who have no other occupation but to attend the synagogue for communal purposes, it is considered to be a village, and the Megillah is read earlier, on the day when people gather in the synagogue.
If a city lacks ten adult men, the very difficulty leads to its solution, and they are considered to be like the inhabitants of a large city and read the Megillah only on the fourteenth.

(9) When does the above leniency - that it is possible to read the Megillah earlier, on the day people gather in the synagogue - apply? When Israel rules itself. In the present era, however, the Megillah is read only at its appropriate times, the fourteenth of Adar and the fifteenth. The inhabitants of villages and cities read on the fourteenth, and the inhabitants of walled cities read on the fifteenth.

(10) The following rules apply when an inhabitant of an unwalled city travels to a walled city, or an inhabitant of a walled city travels to an unwalled city:
If his intent was to return home for the day of the Megillah reading, but he was prevented from returning, he should read the Megillah on the day when it is read in his home. If his intent was not to return home until after the day of the Megillah reading, he should read the Megillah together with the people in the place where he is visiting.
The following rule applies to all those homes adjacent to a walled city which are seen together with it: If there are not more than two thousand cubits between them, they are considered to be part of the walled city, and their inhabitants should read the Megillah on the fifteenth.

(11) When a doubt exists and it is unknown whether a city had been surrounded by a wall at the time of Joshua bin Nun or whether it was surrounded afterwards, its inhabitants should read the Megillah on the day and the night of both the fourteenth and the fifteenth of Adar. They should recite the blessing only when reading on the fourteenth, since this is the time when the Megillah is read in most places in the world.

(12) When the Megillah was read in the first month of Adar and, afterwards, the court proclaimed a leap year, the Megillah should be read again in the second month of Adar at its appropriate time.

(13) The Megillah should not be read on the Sabbath. This is a decree, enacted so that one should not take it in one's hands and bring it to a person who knows how to read it, thus carrying it four cubits in the public domain. Everyone is obligated to read the Megillah, but everyone is not capable of reading it. Thus, there is the possibility for such an error to occur.
For this reason, if the appropriate time for the Megillah to be read falls on the Sabbath, we read it earlier, on the day prior to the Sabbath. We discuss the laws of Purim on that Sabbath to commemorate the fact that it is Purim.

(14) What is implied? When the fourteenth of Adar falls on the Sabbath, the inhabitants of the unwalled cities should read the Megillah earlier, on Friday. The inhabitants of the walled cities should read it at their appropriate time, on Sunday.
When the fifteenth falls on the Sabbath, the inhabitants of the walled cities read the Megillah earlier, on Friday the fourteenth. The inhabitants of the unwalled cities also read on that day, for this is the appropriate time for them to read. Thus in such an instance, everyone reads on the fourteenth.

(1) When a person reads the Megillah in improper sequence, he does not fulfill his obligation. If a person was reading, forgot a verse and read the following verse, went back and read the verse he forgot, and then read a third verse, he does not fulfill his obligation, because he read a verse in improper sequence. What should he do instead? He should begin from the second verse, the verse he forgot, and continue reading the Megillah in its proper order.

(2) Should one encounter a congregation that has already read half of the Megillah, one should not say, "I will read the latter half together with this congregation, and then go back and read the first half," for this is reading in improper sequence. Instead, one should read the entire Megillah from beginning to end in order.
When a person reads a portion and pauses and then goes back and continues reading, since he read in order, he fulfills his obligation, even though the entire Megillah could have been read while he had paused.

(3) A person who reads the Megillah by heart does not fulfill his obligation. A person who speaks a language other than Hebrew and hears the Megillah read in Hebrew written in the holy script fulfills his obligation, although he does not understand what is being read. Similarly, if the Megillah was written in Greek, a person who hears it, even one who speaks Hebrew, fulfills his obligation although he does not understand what is being read.

(4) If, however, it was written in Aramaic or in another language of gentile origin, one who listens to this reading fulfills his obligation only when he understands that language and only when the Megillah is written in that language.
In contrast, if the Megillah was written in Hebrew and one read in Aramaic for a person who understood that tongue, one does not fulfill one's obligation, for one is reading by heart. And since the reader cannot fulfill his obligation, the person hearing it read by him also cannot.

(5) A person who was reading the Megillah without the desired intent does not fulfill his obligation. What is implied? That he was writing a Megillah, explaining it, or checking it: If he had the intent to fulfill his obligation with this reading, his obligation is fulfilled. If he did not have this intent, he did not fulfill his obligation. Should one read while dozing off, he fulfills his obligation, since he is not sound asleep.

(6) When does the statement that a person can fulfill his obligation by reading when writing a Megillah apply? When he intends to fulfill his obligation to read it by reading from the scroll which he is copying. If, however, he intends to fulfill his obligation by reading the scroll that he is writing at present, he does not fulfill his obligation, for one can fulfill one's obligation only by reading from a scroll that was completely written at the time of the reading.

(7) A person who errs while reading the Megillah and reads in an inexact manner fulfills his obligation, for we are not required to read in a precise manner.
A person fulfills his obligation whether he reads it standing or sitting. This applies even when reading for a congregation. Nevertheless, at the outset, out of respect for the congregation, one should not read for the congregation while sitting.
If two, and even if ten, people read the Megillah in unison, both the readers and those who listen to the readers fulfill their obligation. An adult and a child can read the Megillah together, even for the community.

(8) We should not read the Megillah for a congregation from a scroll that contains the other Sacred Writings. Should one read for the congregation from such a scroll, no one fulfills their obligation, unless the portions of parchment on which it is written are larger or smaller than those of the remainder for the scroll, so that it will be distinct.
An individual reading for himself, by contrast, may read from such a scroll even though the portion containing the Megillah is not larger or smaller than the remainder of the scroll, and thus fulfill his obligation.

(9) A Megillah may be written only with ink on g'vil or on k'laf, like a Torah scroll. If it was written with gall-nut juice or vitriol it is acceptable, but if it was written with other tints it is not acceptable.
It must be written on ruled parchment like a Torah scroll. The parchment need not, however, be processed with the intent that it be used for the mitzvah. If it was written on paper or on an animal hide that was not processed or if it was written by a gentile or by a non-believer, it is not acceptable.

(10) The following rules apply when the letters of a Megillah are rubbed out or torn: If a trace of the letters is discernible, the scroll is acceptable, even if most of the letters have been rubbed out. If no trace of the letters is discernible, the scroll is acceptable if the majority of its letters are intact. If not, it is not acceptable.
If the scribe left out certain letters or verses and the reader reads them by heart, he fulfills his obligation.

(11) A Megillah must be sewn together - i.e., all the parchments on which it is written must be joined as a single scroll. It should be sewn only with animal sinews, as a Torah scroll is. If it is sewn with other thread, it is unacceptable.
It is not necessary, however, to sew the entire length of the parchment with animal sinews, as a Torah scroll is sewn. As long as one sews three stitches at one end of the parchment, three stitches in the middle, and three stitches at the other end, it is acceptable. This leniency is taken, because the Megillah is referred to as an "epistle" Esther 9:29.

(12) The reader should read the names of Haman's ten sons and the word which follows, asseret Esther 9:7-10, in one breath, to show the entire people that they were all hung and slain together.
It is a universally accepted Jewish custom that as the reader of the Megillah reads, he spreads the text out as an epistle (to show the miracle). When he concludes, he goes back, rolls up the entire text, and recites the concluding blessing.

(13) On these two days, the fourteenth and the fifteenth of Adar, it is forbidden to eulogize and to fast. This prohibition applies to all people in all places, to the inhabitants of the walled cities who celebrate only the fifteenth and to the inhabitants of the unwalled cities who celebrate only the fourteenth.
In a leap year, it is forbidden to eulogize and to fast on these two dates in the first Adar as well as in the second Adar. When the inhabitants of the villages read the Megillah earlier, on the Monday or Thursday before Purim, they are permitted to eulogize and to fast on the day they read the Megillah, and are forbidden to eulogize and to fast on these two dates, even though they do not read the Megillah on them.

(14) It is a mitzvah for the inhabitants of the villages and unwalled cities to consider the fourteenth of Adar - and for the inhabitants of the walled cities to consider the fifteenth of Adar - as a day of happiness and festivity, when portions of food are sent to one's friends and presents are given to the poor.
It is permitted to work on these days. It is not, however, proper to do so. Our Sages declared, "Whoever works on Purim will never see a sign of blessing."
Should the inhabitants of the villages read the Megillah earlier, on a Monday or a Thursday, and give monetary gifts to the poor on the day on which they read, they fulfill their obligation. The rejoicing and festivities of the Purim holiday, by contrast, should be held only on the day of the fourteenth. If they are held earlier, the participants do not fulfill their obligation. A person who conducts the Purim feast at night does not fulfill his obligation.

(15) What is the nature of our obligation for this feast? A person should eat meat and prepare as attractive a feast as his means permit. He should drink wine until he becomes intoxicated and falls asleep in a stupor.
Similarly, a person is obligated to send two portions of meat, two other cooked dishes, or two other foods to a friend, as implied by Esther 9:22, "sending portions of food one to another" - i.e., two portions to one friend. Whoever sends portions to many friends is praiseworthy. If one does not have the means to send presents of food to a friend, one should exchange one's meal with him, each one sending the other what they had prepared for the Purim feast and in this way fulfill the mitzvah of sending presents of food to one's friends.

(16) One is obligated to distribute charity to the poor on the day of Purim. At the very least, to give each of two poor people one present, be it money, cooked dishes, or other foods, as implied by Esther 9:22 "gifts to the poor" - i.e., two gifts to two poor people.
We should not be discriminating in selecting the recipients of these Purim gifts. Instead, one should give to whomever stretches out his hand. Money given to be distributed on Purim should not be used for other charitable purposes.

(17) It is preferable for a person to be more liberal with his donations to the poor than to be lavish in his preparation of the Purim feast or in sending portions to his friends. For there is no greater and more splendid happiness than to gladden the hearts of the poor, the orphans, the widows, and the converts.
One who brings happiness to the hearts of these unfortunate individuals resembles the Divine Presence, which Isaiah 57:15 describes as having the tendency "to revive the spirit of the lowly and to revive those with broken hearts."

(18) All the books of the Prophets and all the Holy Writings will be nullified in the Messianic era, with the exception of the Book of Esther. It will continue to exist, as will the five books of the Torah and the halachot of the Oral Law, which will never be nullified.
Although all memories of the difficulties endured by our people will be nullified, as Isaiah 65:16 states: "For the former difficulties will be forgotten and for they will be hidden from My eye," the celebration of the days of Purim will not be nullified, as Esther 9:28 states: "And these days of Purim will not pass from among the Jews, nor will their remembrance cease from their seed."