Adam Clarke, on Esth 9:23

“And the Jews undertook to observe with solemnity all they had begun to do at that time, which Mardochai by letters had commanded to be done.”

“The Jews undertook to do as they had begun - They had already kept the fifteenth day, and some of them in the country the fourteenth also, as a day of rejoicing: Mordecai wrote to them to bind themselves and their successors, and all their proselytes, to celebrate this as an annual feast throughout all their generations; and this they undertook to do. And it has been observed among them, in all places of their dispersion, from that day to the present time, without any interruption.”

Imported from an open dataset — not yet checked against the printed edition.