Following their miraculous rescue from the decree of annihilation, the Jews erupted in spontaneous celebration. This organic outpouring of relief occurred even before any official letters were sent to formalize the event. A distinct contrast emerged in the way the victory was observed, based on whether the people lived in open plains without walls or in fortified cities [אבן עזרא, עמנואל הרומי]. Residents of the open towns lacked protective fortresses and the presence of the royal army, leaving them exposed to far greater danger during the conflict. Consequently, when they finally rested from their enemies on the fourteenth day of the month, their overwhelming sense of deliverance prompted them to immediately declare it a day of rejoicing [מלבי״ם, יוסף אבן יחיא, שטיינזלץ]. In contrast, the fighting in the fortified capital, which was the epicenter of the miracle and home to the most prominent members of the enemy nation, continued for an additional day. Thus, the residents of the walled city rested and celebrated only on the fifteenth [רלב״ג].
The primary approach among commentators is that the distinction between open and walled cities was not determined by their physical status during this Persian era, but rather by their standing dating back to the days of Joshua. This historical anchor serves a dual purpose. First, it honors the Land of Israel, whose cities lay in ruins at the time, elevating them to the same level of importance as the magnificent Persian capital. Second, it pays tribute to Joshua, the original leader who waged war against the ancestors of the very enemy they had just defeated [רש״י, רלב״ג, תורה תמימה].
The ensuing celebration was characterized by four specific expressions: joy, feasting, observing a holiday, and sending portions of ready-to-eat food to one another [אבן עזרא]. These elements were deliberately established as exact counterweights to the four acts of grief the Jews had taken upon themselves when the decree was first issued: mourning, fasting, weeping, and wailing [אלשיך, מגילת סתרים]. Joy replaced weeping, feasting replaced fasting, and the holiday replaced mourning. The act of sending food portions served as the counterpart to wailing. Just as wailing involves a communal gathering where people share in each other's sorrow, the exchange of food expresses connection, love, and mutual gratitude. This profound display of unity directly rectified Haman's accusation that the Jews were a scattered and divided people, demonstrating instead that their redemption was achieved through solidarity and mutual responsibility.
Initially, the residents of the open towns decided on their own to designate their day of victory as a formal holiday, which entailed wearing festive garments and observing a strict prohibition against working [יוסף אבן יחיא]. They believed that their survival marked the beginning of a complete redemption, akin to the Exodus from Egypt. Furthermore, they felt their original transgression had been partaking in the foreign king's decadent banquet, and they sought to atone for this by establishing a sacred, commanded feast [מגילת סתרים]. However, Mordecai and the sages later revoked the prohibition against working, recognizing that a cessation of labor would lead to financial loss and ultimately harm the impoverished. Instead, Mordecai replaced the formal holiday with the Commandment of giving gifts to the poor. Mordecai understood that the people's true sin had been bowing to an idol, a desecration of God's name that demanded atonement specifically through acts of mercy and charity. Moreover, he recognized that the recent miracle was a physical rescue rather than a complete spiritual redemption, and therefore it did not warrant a permanent prohibition against labor for future generations [אלשיך, מלבי״ם, מגילת סתרים].
On a deeper conceptual level, the open, unwalled city serves as an allegory for an individual who is not yet spiritually complete and remains vulnerable to the attacks of the evil inclination. The ultimate purpose of the joy and feasting during this time is to reach a state of intoxication that entirely severs the grip of this evil inclination, elevating the person to a state where they can no longer distinguish between the cursed enemy and the blessed hero [מחיר יין].