Following the great rescue and the spontaneous joy that erupted among the people, a need arose to cement the miracle for all future generations. Moving from a voluntary celebration to an eternal obligation required detailed documentation to persuade the Jewish communities scattered throughout the empire. The primary approach among commentators is that this record was the Scroll of Esther itself, capturing the core events exactly as they happened [רש״י, יוסף אבן יחיא, ביאור שטיינזלץ, עמנואל הרומי]. At this initial stage, Mordecai alone authored the text [אבן עזרא, עמנואל הרומי].
A comprehensive account was necessary because Jews living far from the capital city of Shushan did not fully grasp the magnitude of the danger or the resulting miracle. Many assumed the original decree was merely a plot to confiscate their wealth, or that the king had simply changed his mind at the request of his queen. Mordecai detailed the sequence of events to make it clear that the decree called for total annihilation, that Esther had actively risked her life, and that the ultimate salvation came entirely from God [אלשיך]. Furthermore, these distant communities were unaware that Haman's original order of destruction was never officially revoked. It was only neutralized by the dread Mordecai instilled in the local officials. The written account revealed to them that they too had been in immediate, mortal danger [מלבי״ם].
To ensure the celebration endured, Mordecai sent official letters alongside the scroll to transition the spontaneous joy of the first year into a permanent, commanded practice. This shift was vital because a person who fulfills a formal command achieves more than one who acts voluntarily [מנות הלוי]. These dispatches instructed the people to establish the days of Purim through feasting, sending portions of food to one another, and giving gifts to the poor [צאינה וראינה]. The goal was not merely to preserve an ancient memory, but to ensure that in every year, Jews would celebrate as if the miracle were unfolding that very day [מגילת סתרים]. Additionally, the permanent record stood as a warning to future generations, deterring any potential enemies from speaking against God and His people [יוסף אבן יחיא].
The arrival of these dispatches also shaped a familiar custom regarding the praises sung on Purim. Originally, Jews in the distant provinces only knew of Haman's downfall, leading them to curse him, yet they remained unaware of who had actually orchestrated their rescue. It was only when Mordecai's letters reached them that they understood his pivotal role and began to bless him as well. Consequently, the tradition was established to first declare the curse upon Haman and only afterward pronounce the blessing upon Mordecai [צאינה וראינה].