18:3
v'hineh sh'loshah a'nashim
And behold! Three men...
The word hineh,
behold, suggests the unexpected [Baal HaTurim
VaYikra 13:6]. The 'men' were really angels [as
obvious from the specific
reference to them as angels in 19:1]
in the guise of men (Bava Metzia 86b; Rashi to v. 1 s.v. k'chom hayom; Rambam).
Three different angels were sent because each had a different function: One [Michael] to inform him of Sarah's conception [v14]; one {Gavriel]
to overthrow Sedom [19:24]; and one [Rafael] to heal Avraham, [no
Scriptural verse is cited for the latter; it is a Rabbinic tradition]
for one angel does not perform two missions [and likewise two angels do
not perform one (Midrash)] (Rashi).
Rashi goes on to explain that the interpretation [that each mission was
performed by a single angel rather than all the angels sharing the
performance of each mission [Mizrachi] is evident from the text itself,
for the Torah speaks of their eating [v8] and talking [v9] in the
plural; while the performance of each of their commissions is related in
the singular. For example regarding the announcement of Sarah's child
[v10]; and the destruction of Sedom [19:21, 22] the angels are
referred to in singular, [especially 19:25: 'he overthrew those cities'
(Bava Metzia 86b).] Rafael, who healed Avraham, went on from there to
save Lot. {That Rafael was charged with both missions did not violate
the principle of 'one angel does not perform two missions' for the
missions were not simultaneous as the second mission was in another
place and the angel was commanded about it only after he had completed
his first mission; therefore a fourth angel was not required.
Additionally, since healing and rescue are related missions, and both
were done for the benefit of Abraham, one angel could be charged with
both tasks (Ramban); see Gur Aryeh.]
Malbim, in a lengthy dissertation to v3, disagrees with those who
maintain that Avraham saw these angels in a vision or that they assumed
human corporeality visible only to him. He emphasizes that a proper
understanding of the text dictates that the angels were visible to
everyone as men, for even the people of Sedom - who were surely not
prophets! - saw and spoke to them [see Ramban cited to
v1].