Robert Spencer has the installment here
Spencer comments on the Koran's views on adoption (given in Verse 4
[T]he passage is intended to end the practice of adoption, starting with Muhammad's own family. Ibn Kathir explains: "This was revealed concerning Zayd bin Harithah…the freed servant of the Prophet. The Prophet had adopted him before prophethood, and he was known as Zayd bin Muhammad. Allah wanted to put an end to this naming and attribution." An adopted son should be known by the name of his natural father: he can never truly enter into his adoptive household (v. 5).
Why was Allah so intent on ending the practice of adoption? Because Muhammad wanted to marry Zayd's ex-wife, Zaynab bint Jahsh — and as a result of his dalliance with his former daughter-in-law, says Maududi, "the hypocrites and the Jews and the mushriks [unbelievers] who were already bent on mischief would get a fresh excuse to start a propaganda campaign against Islam." So Allah here emphasizes that an adopted son cannot be a true son, and so by extension Zaynab was never really Muhammad's daughter-in-law at all, and there is no cause for scandal.
The remainder of this section of the sura tells about the Battle of the Trench - for additional background see Wikipedia.
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Labels: Koran, Religion