On the night of Purim, the Megila is read after the recitation of the half-Kaddish following the Shemona Esrei. The Chazan reading the Megila first recites the three Berachot, including the Beracha of She'hecheyanu. When She'hecheyanu is recited, both the Chazan and the congregation should have in mind that this Beracha pertains to all the Mitzvot of Purim: the nighttime and daytime Megila readings, the Purim meal, Mishlo'ach Manot, and Matanot La'evyonim (gifts to the poor). The Chazan's recitation of this Beracha fulfills the obligation on behalf of the entire congregation, and they therefore must not answer "Baruch Hu U'varuch Shemo" during the Beracha.
One adds "Al Ha'nissim" and "Bi'mei Mordechai" in Birkat Ha'mazon and Shemona Esrei throughout Purim, both by day and by night. If one forgot to insert Al Ha'nissim, he does not repeat Birkat Ha'mazon or Shemona Esrei. However, one who forgot to recite Al Ha'nissim during Birkat Hamazon should add it in the "Ha'rachaman" section of Birkat Ha'mazon, by reciting, "Ha'rachaman Hu Ya'aseh Nissim… Bi'mei Mordechai…" If one forgot to insert Al Ha'nissim in Shemona Esrei, he may add it in between the sentences of "Yiheyu Le'ratzon Imrei Fi" and "Oseh Shalom."
We do not recite Hallel on Purim, because the reading of the Megila serves as a substitute for the recitation of Hallel. Therefore, the Chida (1724-1806) ruled that a person who does not have access to a valid Megila on Purim should recite Hallel, though without a Beracha.
Tachanun is of course omitted on Purim.
During the Shacharit service on Purim morning, we read from the Torah the section towards the end of Parashat Beshalach which begins, "Va'yavo Amalek" and tells of the battle waged between Amalek and Benei Yisrael in the wilderness. We read the Torah before reading the Megila due to the principle that precedence is given to the more frequent Mitzva; since the Torah is read more frequently than the Megila, it takes precedence.
Although the section of "Va'yavo Amalek" contains only nine verses, and generally a minimum of ten verses is required when reading the Torah, this reading is nevertheless permissible because the nine verses constitute a self-contained textual unit. Still, our custom is to repeat the final verse so that we will have read ten verses.
Our custom is to recite Ashrei and the first two verses of U'va Le'tziyon immediately following the Torah reading, before the reading of the Megila. Then, after the Megila reading, we continue with "Ve'ata Kadosh…" We do this because in the Book of Tehiilim (22), the verse "Ve'ata Kadosh" is preceded by the verse, "My G-d, during the day I call and you answer not; and at nighttime – and there is no silence for me," which the Sages interpret as a reference to the Megila reading. It is therefore appropriate to recite the verse of "Ve'ata Kadosh" immediately following the reading of the Megila.
The custom is to kiss one's Tefillin during the Megila reading, when the Chazan reaches the word "Vi'kar" ("and glory") in the verse "La'yehudim Hayeta Ora…Vi'kar" ("The Jews had light…and glory" – 8:16), because the Gemara explains the word "Vi'kar" as a reference to Tefillin.
When the Chazan reaches the phrase in the Megila, "Kol Divrei Ha'igeret Ha'zot" ("all the words of this letter" – 9:26), he gently shakes the Megila scroll.
Only the Chazan must have the entire Megila unraveled before him as he reads; the rest of the congregation who listen to his reading need not unroll the entire Megila during the reading.
There are four verses which the congregation customarily reads aloud before the Chazan during the Megila reading: "Ish Yehudi…" (2:5); "U'Mordechai Yatza…" (8:15); "La'yehudim Hayeta…" (8:16); and the Megila's final verse – "Ki Mordechai Ha'yehudi…" (9:3).
There are two verses regarding which some debate exists concerning the correct pronunciation of a given word: "La'harog"/"Va'la'harog" – 8:11; "Bifneihem"/"Lifneihem" – 9:3). The custom is therefore to read these verses twice, to satisfy both views.
It is forbidden to speak during the reading of the Megila, except for matters related to the Megila reading. One must listen attentively to the entire reading, from beginning to end.
The obligation of Matanot La'evyonim (gifts to the poor) requires giving to two poor people the amount of money with which each can purchase a meal. This value is estimated at $5, and therefore one must give a minimum of $10 for Matanot La'evyonim. If one gives on behalf of his wife, as well, he must give $20.
