אבן עזרא — והנה שלשה אנשים

Q — Chazal (cited by Rashi) reasoned that each of the three angels visiting Avraham had exactly one mission — one to announce Sarah's birth, one to destroy Sedom, one to heal Avraham (then save Lot) — based on "אין מלאך אחד עושה שתי שליחויות."

A — Ibn Ezra brings three textual objections that overturn this principle: (1) the instruction to Lot to gather his family is given by BOTH angels — "ויאמרו האנשים אל לוט" — not just the rescuing one; (2) the destruction is described as the mission of both — "כי משחיתים אנחנו את המקום הזה... וישלחנו ה' לשחתה"; (3) the same angel who tells Lot "כי לא אוכל לעשות דבר עד באך שמה" (i.e., the destroyer) is the one Lot pleads with about Tzo'ar — meaning destroyer and savior are one angel. Conclusion, explicitly against Chazal: "מלאך אחד עושה שתי שליחויות ושני מלאכים עושים שליחות אחת." Ibn Ezra opens the piece by citing Chazal's principle and then in chapter 19 demolishes it textually.