Sforno on Deuteronomy 29:22/ספורנו על דברים כ״ט:כ״ב

1'גפרית ומלח....במהפכת סדום אשר הפך ה, the people seeing this know full well that this was not something accidental but that it is a finger of G’d. The comparison is based on Sodom seeing that its destruction had both been predicted to Avraham and confirmed by Lot and his daughters who were survivors of that event.