They made the rule to keep Purim on the set days, like Mordecai and Esther had said. They also set the way for the days of not eating and sad crying before. ✅
in order to confirm these days of Purim at their appointed time, just as Mordecai the Jew and Queen Esther had established them and had committed themselves and their descendants to the times of fasting and lamentation.
KJV
To confirm these days of Purim in their times [appointed], according as Mordecai the Jew and Esther the queen had enjoined them, and as they had decreed for themselves and for their seed, the matters of the fastings and their cry.
ASV
to confirm these days of Purim in their appointed times, according as Mordecai the Jew and Esther the queen had enjoined them, and as they had ordained for themselves and for their seed, in the matter of the fastings and their cry.