The Wisdom behind the Multiple Wives of the Prophet

[Al-Ubbi said:]
Al-Shafi'i said: "Allah (Glorified is He) singled out the Messenger of
Allah by obligating on him things which He alleviated from other than
him, in order to increase his (Allah bless him and grant him peace)
sanctity, and He permitted for him things which He made unlawful for
other than him, in order to increase his honour and his exaltation."
From this category is [thepermission of] having more than four
[wives]. This was permitted [for him] so that he ascends in the hearts
of the Arabs in esteem and glory, because they would boast over sexual
prowess. Furthermore, in terms of perfect power and moderate
constitution, he was at the level of perfection attested to by the
reports, and whoever was such, the precursors to this door [of
perfection] would be dominant over him.
Furthermore, those besides him were forbidden from more than four
[wives] for fearof injustice, as alluded to in the verse: "But, if you
fear that you will not maintain equity, then [marry only] one." (4:3)
And this reason is inapplicable with respectto him (Allah bless him
and grant him peace).
That this is the reason forforbidding those besides him is proven by
[the fact] that Allah (Glorified is He) permitted for them whatever
[quantity] of slave women they have [financial] ability over, asin His
(Exalted is He) statement: "Or what your right hands possess" (4:3),
because slave women did not have rights over sexual intercourse such
that injustice would be fearedtherein.
Furthermore, it is not permissible for him [i.e. the Prophet (peace be
upon him)] to seek pleasure in what is not permissible for him, nor to
seek what is in the hands of men, and the condition at that time was
not accommodating for the acquisition of [many] slave women. Hence,
free women were made available to him. And Allah chose for him the
best of the two kinds [i.e. free women over slave women]. This is why
some of the Salaf said: "Free [non-Muslim] covenanted women werenot
permissible for him to marry, as opposed to other than him from his
ummah." Others said: "So that a disbeliever would not become a mother
of the believers."
This is in Sharh al-Ubbi .
The weak slave (Allah pardon him) says:
The teacher of our teachers, Hakim al-Ummah al-Thanawi (may Allah
sanctify his secret), mentioned another wisdom behind the abundance of
his (Allah bless him and grant him peace) wives, which is that:
He (upon him blessing and peace) was sent to this world to be an
excellent example in all things, and so that his ummah imitates him in
all walks of life, and in order for this to be possible it is
necessary that no part of his personal or his communal life is hidden
to his ummah, and that the ummah are privy to the circumstances of his
house and his private lifeby that degree of certainty and that
abundance [of reports] by which they know his circumstances outside
the house. And indeed these circumstances are not revealed to any
besides his (Allah bless him and grant him peace) wives, and this is
why the number of his (Allah bless him and grant him peace) wives
after Khadijah, the Magnificent, reached ten,because ten is the least
number for recurrent transmission ( tawatur ), and when the number of
his wives reached ten, Allah (Exalted is He) forbade him from
increasing on this number, as was said in the explanation of His
(Exalted is He) saying: "Women are not permitted for you thereafter"
(33:52) to the end [of the verse]. Refer to al-Tafsir al-Kabir .
And in this number of wives there are three secrets which Shaykh
al-Thanawi (Allah have mercy on him) mentioned:
First, that it is the least of "the plurality of abundance" ( jam' al-kathrah ).
Second, that it is the leastnumber for recurrent transmission ( tawatur ).
Third, that it agrees with the number of years the Messenger of Allah
(Allah bless him and grant him peace) resided in Madinah (i.e. 10).
This is from his treatise Kathrat al-Azwaj li Sahib al-Mi'raj .
This is supported by the fact that he (Allah bless him and grant him
peace) did not spend his youth and his period of manliness but with
one widowed woman many years his senior, despite what was presented
before him of chaste Arab virgins; and his wives did not increase in
number except after he reached fifty three years of age, and all of
them were widows, besides 'A'ishah (Allah be pleased with her). Would
one who does not wish but tofulfil his desires and satisfy his lust do
this? Never! Then again, never!But his (Allah bless him and grant him
peace) objective was only to make the conditions of his house reach
the ummah by that abundance [of reports] by which his circumstances
outside the house reached [them], and that would not have been
possible unless his wives were no fewer than ten. This is why we see
that about half of religion did not reach us but through the medium of
his (Allah bless him and grant him peace) wives.
(Takmilah Fath al-Mulhim 1:113-4)