‘As for a woman who has apostatized, it is unlawful to marry her whatever religion she may have embraced, because she is not granted the legal standing of the community to which she has moved so as to be left upon it; consequently, the prohibition in her case is even more certain.’
He also says in the chapter entitled “The Apostate,” 8/130: ‘If he contracts a marriage, that marriage is not valid, for he is not allowed to remain in the state of matrimony; and whatever a person is not allowed to remain upon, its very formation is disallowed—just like the marriage of a disbeliever to a Muslim woman.’1
You can see, then, that he has explicitly ruled marriage to a female apostate forbidden and the marriage contracted by a male apostate invalid. What, then, if apostasy occurs after the marriage contract has been concluded?
He states in al-Mughnī 6/298: ‘If either spouse apostatizes before consummation, the marriage is annulled immediately and neither inherits from the other. If the apostasy takes place after consummation, there are two narrations: according to one, separation occurs at once; according to the other, it is postponed until the waiting period ends.’
And in al-Mughnī 6/639 he writes: ‘The dissolution of marriage on account of apostasy before consummation is the view held by the majority of scholars,’ and he then supplies the supporting proofs. He likewise notes that