EXTRA · Parashas Vayeira · Passuk 18:28
Supplementary classical material; Torah Temimah lists no citation under this passuk.
“Perhaps the fifty righteous will lack five; will You destroy the whole city for lack of five?” And He said, “I will not destroy if I find there forty-five.”
Rashi on Genesis 18:28 (and parallel midrashic tradition on the descending numbers).
Sefaria — Rashi on Genesis 18:28
English: “Perhaps they will lack.” Avraham said: for five You will not destroy — meaning the righteous of the generation together with forty-five, or perhaps the merit of the three Patriarchs will assist together with forty-five.
Derash on the verse (Rashi / Midrash) — not a formal named middah of the 13. The descending numbers are treated as a deliberate bargaining strategy that relies on zechus Avos.
Advocacy for a city may rest on the merit of even a reduced number of righteous, and on the enduring credit of the Patriarchs, teaching the power of intercession and collective merit.