で role in 他言無用でお願いします


で is a hard particle for me because I see a strange use of it that I don't
understand.

For example, I bump up in this sentence

> 他言無用{たごんむよう} **で** お願いします

I know that で is used to indicate an action that occurred inside a place (
_dance inside the house_ ), or used to clarify by what means the action has
been done ( _went by bus_ ). But this is not one of these usages.

What does で mean here?




> 「​他言無用 {たごんむよう} **​で** お願{ねが}いします。」 ("Please keep this a secret.")

The 「で」 here indicates the circumstances/conditions under which one performs
an action.

The conditions requested by the speaker here are 「他言無用」 ("mum's the word").

The action is 「お願いします」, which is difficult to translate. It is like "please
act ~~", "please do ~~", " **please handle the matter** ", etc.

