Аль-Мумтахана 60:10

O you who believe, when believing women come to you, [saying] with their tongues [that they are], emigrating, from the [company of] disbelievers — [this was] following the truce concluded with them [the disbelievers] at al-Hudaybiyya to the effect that if any of their number should go to [join] the believers, that person should be sent back — test them, by making them swear that they had only gone forth [from Mecca] because of their [sincere] wish to embrace Islam, and not out of some hatred for their disbelieving husbands, nor because they might be enamoured by some Muslim man: that was how the Prophet (s) used to take from them their oaths. God knows best [the state of] their faith. Then, if you know them, if you suppose them, on the basis of their oaths, to be believers, do not send them back to the disbelievers. They [the women] are not lawful for them, nor are they [the disbelievers] lawful for them. And give them, that is to say, their disbelieving husbands, what they have expended, on them [on such women], in the way of dowries. And you would not be at fault if you marry them, on that [previous] condition, when you have given them their dowries. And do not hold on (read tumassikū or tumsikū) to the [conjugal] ties of disbelieving women, your wives, for your Islam automatically prohibits you from this, or [to the ties of] those apostatising women who return to the idolaters, for [likewise] their apostatising automatically prohibits you from marrying them, and ask for, demand, [the return of] what you have expended, on these women, of dowries, in the event of apostasy, from those disbelievers to whom they are married. And let them ask for what they have expended, on those women who have emigrated, as explained above, that it may be repaid to them. That is God’s judgement. He judges between you, therewith, and God is Knower, Wise.