Page "Purim" Paragraph 25

The first religious ceremony ordained for the celebration of Purim is the reading of the Book of Esther ( the " Megillah ") in the synagogue, a regulation ascribed in the Talmud ( Megillah 2a ) to the Sages of the Great Assembly, of which Mordecai is reported to have been a member.

Originally this enactment was for the 14th of Adar only ; later, however, Rabbi Joshua ben Levi ( 3rd century CE ) prescribed that the Megillah should also be read on the eve of Purim.

Further, he obliged women to attend the reading of the Megillah, in as much as it was a woman, Queen Esther, through whom the miraculous deliverance of the Jews was accomplished.