וְל֤וֹא הָֽיְתָה֙ סְדֹ֣ם אֲחוֹתֵ֔ךְ לִשְׁמוּעָ֖ה בְּפִ֑יךְ בְּי֖וֹם גְּאוֹנָֽיִךְ׃
און איז ניט סדום דײַן שװעסטערגעװען אַ גערײד אין דײַן מױל, אין דעם טאָג פֿון דײַן שטאָלץ,
Rashi
Now, was not Sodom your sister, etc. This is a [rhetorical] question.
Rashi
a report in your mouth [by which] to reprove many and to say, Beware that you should not be overturned like Sodom, as though it were recent news to you.