Esther 9:31

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.
BSB · Berean Standard Bible
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.

Note themselves: Heb. their souls

KJV · King James Version
to confirm these days of Purim in their appointed times, as Mordecai the Jew and Esther the queen had decreed, and as they had imposed upon themselves and their descendants in the matter of the fastings and their mourning.
WEB · World English Bible
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.
ASV · American Standard Version

Related passages

From the Treasury of Scripture Knowledge, grouped by the word they explain.

themselves
Heb. their souls. and for their seed.
Esther 9:27
the fastings
Esther 4:3, 16; Jonah 3:2–9