וַיֹּ֨אמֶר יְהוָ֜ה אֶל־מֹשֶׁ֗ה כְּתֹ֨ב זֹ֤את זִכָּרוֹן֙ בַּסֵּ֔פֶר וְשִׂ֖ים בְּאָזְנֵ֣י יְהוֹשֻׁ֑עַ כִּֽי־מָחֹ֤ה אֶמְחֶה֙ אֶת־זֵ֣כֶר עֲמָלֵ֔ק מִתַּ֖חַת הַשָּׁמָֽיִם׃
永恆者對摩西說：«你要把這事寫在書上作為紀念，又要說給約書亞聽，因為我必將亞瑪力的記念從天下徹底抹去。»
Mishnah Megillah
The Megillah is read on the eleventh, the twelfth, the thirteenth, the fourteenth, and the fifteenth [of Adar], never earlier and never later. Cities which have been walled since the days of Joshua ben Nun read on the fifteenth; villages and large towns read on the fourteenth, Except that villages move the reading up to the day of gathering.
Mishnah Megillah
If one reads the Megillah out of order, he has not fulfilled his obligation. If he reads it by heart, if he reads it in a translation [targum], or in any other language, he has not fulfilled his obligation. But they may read it to those who do not understand Hebrew in a language other than Hebrew. One who doesn’t understand Hebrew who heard it in Assyrian [Hebrew], has fulfilled his obligation.