'Edict' in the Bible

Now in the twelfth month (that is, the month of Adar) on the thirteenth day when the king’s command and edict were about to be executed, on the [very] day when the enemies of the Jews had hoped to gain power over them [and slaughter them], it happened the other way around so that the Jews themselves gained power over those who hated them.

Then they approached and spoke before the king regarding his injunction, “Have you not signed an injunction that anyone who petitions (prays to) any god or man except you, O king, within the designated thirty days, is to be thrown into the den of lions?” The king answered, “The statement is true, in accordance with the law of the Medes and Persians, which may not be altered or revoked.”