פּירוש אויף בראשית 18:2

והנה שלשה אנשים AND BEHOLD THREE MEN — one to announce to Sarah the birth of a son, one to overthrow Sodom, and one to cure Abraham, for one angel does not carry out two commissions (Genesis Rabbah 50:2). You may know that this is so because throughout this section it (Scripture) mentions them in the plural — “and they ate” (Genesis 18:8), “and they said unto him” (Genesis 18:9) — whilst in the case of the announcement it states, (Genesis 18:10) “And he said, I will certainly return unto thee”, and with regard to the overthrow of Sodom it says (Genesis 19:22) “For “I” cannot do anything” and (Genesis 19:21) “that “I” will not overthrow [the city]”. Raphael who healed Abraham went thence to rescue Lot; that explains what is stated (Genesis 19:17) “And it came to pass when they had brought them forth, that he said, Escape for thy life”, for you learn from this that only one of these acted as Deliverer

And he saw and behold, 3 men: according to the simple understanding these were normal men for we don't find that angels eat and drink and recline in a man's house like in the house of Lot, like we said with the angel said to Manoach ‘If you detain me, I will not eat your food, etc...'. However, one should not reject the words of the Sages, who also viewed them as angels with awareness of earthly matters. And in any case, it is forbidden to teach that they were angels as proof of their physicality, as this could support the heretical argument of those who claim the three were three parts of a god. If so, why would one of those parts need to enter a woman—as did their 'christian,' who took on flesh? Here, they had flesh to eat and drink and did not need to enter a woman’s womb."

והנה שלשה אנשים, according to Rashi, these “three men,” were in fact three angels with different tasks to perform. One was Rafael, whose task it was to heal Avraham from the wounds of the circumcision. (this is based on Talmud Baba Metzia 86. He then went on to save Lot.) Of the two angels who proceeded on to Sodom, one was Michael. If it had been so this would contradict the statement of our sages that an angel is assigned only one task at a time. Some Rabbis consider saving Lot as similar in principle to healing Avraham, so that there would be no contradiction.