The word דבר (speak/speech) sometimes indicates a theme or essence, like על דבר שרי (because of Sarai)⁶³⁰. And the sages of blessed memory always explained this according to its primary meaning from the theme of pronounced speech, from which it is borrowed. As such are the ways with all metaphoric words (as in Rule 248).

The primary meaning of the word דבר is pronounced speech. The Torah often borrows the word דבר to indicate a theme or essence.

footnotes: ⁶³⁰ Genesis 12:17.