Yesterday, we explained how most places around the world would celebrate Purim tomorrow, Friday, the 14th of Adar.
On the other hand, in the holy city of Jerusalem, which is walled since the days of Yehoshua bin Nun, Purim is celebrated on the 15th of Adar every year. Nevertheless, when the 15th of Adar coincides with Shabbat as it does this year, the Megillah is read in Jerusalem on Friday, the 14th of Adar, as it is throughout the rest of the world.
The reason for this is because of Sages decreed that the Megillah may not be read on Shabbat, for everyone is obligated to read the Megillah but not everyone is expert in doing so properly. Thus, one must bring one’s Megillah to a place where there are experts who know how to read it (such as a synagogue) and in doing so, one may inadvertently transgress the prohibition of carrying from a private domain to a public domain and the like (where there is no Eruv), which constitutes a Torah prohibition. Our Sages therefore enacted that when the 15th of Adar falls out on Shabbat, Megillah reading is moved up to Friday, the 14th of Adar.
This concept is discussed by the Gemara (Megillah 4b), the Rambam, and Maran Ha’Shulchan Aruch. Another reason for this is because the needy long for the reading of the Megillah, for they know that charity funds are distributed to the poor on the day of the reading of the Megillah and on Shabbat, Matanot La’Evyonim may not be distributed. Thus, the Sages enacted that the Megillah be read the day before.
Therefore, this year (5781) when the 15th of Adar coincides with Shabbat, the Megillah will be read in Jerusalem on the same day it is read throughout the rest of the world which is on Friday. The Mitzvah of Matanot La’Evyonim should likewise be performed on Friday, the same day the Megillah is read.
Nevertheless, the Purim feast should be held in Jerusalem on Sunday this year. Although the feast is held on Sunday, the Mitzvah of Matanot La’Evyonim must be performed on Friday, for as a result of the endearment of the miracle during the time the Megillah is being read, one’s heart opens and one donates more generously to the poor.
On Shabbat, the 15th of Adar, in Jerusalem, “Al Ha’Nissim” should be inserted into all Shabbat prayers. “Al Ha’Nissim” is likewise inserted into Birkat Hamazon throughout Shabbat as is the case every year on the 15th of Adar in Jerusalem.
The Talmud Yerushalmi explains that the reason why the Purim feast is not held on Shabbat is because the verse in the Megillah states, “To make them days of feasting and merriment,” and Shabbat was not made a day of feasting and merriment by the Sages; rather, Shabbat preceded their enactment. Nevertheless, the Poskim write that it is appropriate to add a special food to the Shabbat meal in honor of Purim.
The Mitzvah of Mishloach Manot is likewise to be fulfilled on Sunday, the same day the Purim feast is held. However, “Al Ha’Nissim” should not be inserted into Birkat Hamazon of this meal since it is no longer actually Purim. Some act stringently and send Mishloach Manot on Shabbat as well (where there is an Eruv) and this is indeed admirable.