Albert Barnes Commentary Esther 1:22

"for he sent letters into all the king`s provinces, into every province according to the writing thereof, and to every people after their language, that every man should bear rule in his own house, and should speak according to the language of his people." — Esther 1:22 (ASV)

He sent letters - The Persian system of posts incidentally noticed in the present book (Esther 3:12–15; Esther 8:9–14), is in entire harmony with the accounts of Herodotus and Xenophon.

Into every province according to its own script - The practice of the Persians to address proclamations to the subject-nations in their own speech, and not merely in the language of the conqueror, is illustrated by the bilingual and trilingual inscriptions of the Achaemenian monarchs, from Cyrus to Artaxerxes Ochus, each inscription being of the nature of a proclamation.

The decree was not unnecessary. The undue influence of women in domestic, and even in public, matters is a feature of the ancient Persian monarchy. Atossa completely ruled Darius. Xerxes himself was, in his later years, shamefully subject to Amestris. The example of the court would naturally infect the people. The decree therefore would be a protest, even if ineffectual, against a real and growing evil.

And that it should be published... - Render it: and speak the language of his own people; in the sense that the wife's language, if different from her husband's, should in no case be allowed to prevail in the household.