2 Maccabees 15:36

36 And they all decreed by public vote never to let this day go unobserved, but to celebrate the thirteenth day of the twelfth month—which is called Adar in the Aramaic language—the day before Mordecai's day.

2 Maccabees 15:36 In-Context

34 And they all, looking to heaven, blessed the Lord who had manifested himself, saying, "Blessed is he who has kept his own place undefiled!"
35 Judas hung Nicanor's head from the citadel, a clear and conspicuous sign to everyone of the help of the Lord.
36 And they all decreed by public vote never to let this day go unobserved, but to celebrate the thirteenth day of the twelfth month—which is called Adar in the Aramaic language—the day before Mordecai's day.
37 This, then, is how matters turned out with Nicanor, and from that time the city has been in the possession of the Hebrews. So I will here end my story.
38 If it is well told and to the point, that is what I myself desired; if it is poorly done and mediocre, that was the best I could do.
New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.