Surah An-Nisa', Chapter 4, Section 4
وَالْمُحْصَنَاتُ مِنَ النِّسَاء إِلاَّ مَا مَلَكَتْ أَيْمَانُكُمْ كِتَابَ اللّهِ عَلَيْكُمْ وَأُحِلَّ لَكُم مَّا وَرَاء ذَلِكُمْ أَن تَبْتَغُواْ بِأَمْوَالِكُم مُّحْصِنِينَ غَيْرَ مُسَافِحِينَ فَمَا اسْتَمْتَعْتُم بِهِ مِنْهُنَّ فَآتُوهُنَّ أُجُورَهُنَّ فَرِيضَةً وَلاَ جُنَاحَ عَلَيْكُمْ فِيمَا تَرَاضَيْتُم بِهِ مِن بَعْدِ الْفَرِيضَةِ إِنَّ اللّهَ كَانَ عَلِيمًا حَكِيمًا
24. "And all married women (are forbidden unto you to marry) except those whom your right hands possess (by Allah's decree in the battle against infidels). It is a written legislation of Allah unto you; and lawful for you are (all women) besides those that you may seek (them) by means of your wealth (as dower) taking them into marriage and not committing fornication. Then as to those of whom you seek content (by temporary marriage), give them their dowries as a duty; and there is no blame on you in whatever you mutually agree after the duty. Verily Allah is All-Knowing, All-Wise."
For non-Muslims, captivity is counted as divorce. It is like the Faith of a woman that when her husband continues his infidelity and the woman has embraced Islam; the very belief separates her from her husband.
To take in marriage a woman who has husband is unlawful from the point of Islam. The woman may be from any nation and with any religion.
But captivity is like divorce, and a captive woman should observe a waiting term for one month (one menstruation) from the time she is captured, and if she is in pregnancy period, she must wait until she is delivered of her child. Thus, during this period, no conjugal connection is admissible with her.
This matrimonial device, as a permanent or contemporary spouse, is better than the device of returning her to the infidels or leaving her alone with no guardian.
According to several traditions narrated from the holy Imams of Ahlul-Bayt (as), and also according to many commentary books recorded by the scholars of the Sunnis, this phrase of the verse refers to temporary marriage where the above-mentioned holy verse says:
وَمَن لَّمْ يَسْتَطِعْ مِنكُمْ طَوْلاً أَن يَنكِحَ الْمُحْصَنَاتِ الْمُؤْمِنَاتِ فَمِن مِّا مَلَكَتْ أَيْمَانُكُم مِّن فَتَيَاتِكُمُ الْمُؤْمِنَاتِ وَاللّهُ أَعْلَمُ بِإِيمَانِكُمْ بَعْضُكُم مِّن بَعْضٍ فَانكِحُوهُنَّ بِإِذْنِ أَهْلِهِنَّ وَآتُوهُنَّ أُجُورَهُنَّ بِالْمَعْرُوفِ مُحْصَنَاتٍ غَيْرَ مُسَافِحَاتٍ وَلاَ مُتَّخِذَاتِ أَخْدَانٍ فَإِذَا أُحْصِنَّ فَإِنْ أَتَيْنَ بِفَاحِشَةٍ فَعَلَيْهِنَّ نِصْفُ مَا عَلَى الْمُحْصَنَاتِ مِنَ الْعَذَابِ ذَلِكَ لِمَنْ خَشِيَ الْعَنَتَ مِنْكُمْ وَأَن تَصْبِرُواْ خَيْرٌ لَّكُمْ وَاللّهُ غَفُورٌ رَّحِيمٌ
25. "And whoever among you is not able to financially afford to marry free believing women, then (let him marry) of those (slaves or captives) whom your right hands possess from among your believing maidens; and Allah better knows your faith; you are (sprung) one from the other, so marry them with the permission of their masters, and give them their dowries in fairness, they being chaste, not committing lewdness, nor taking paramours. And if when they are married they commit lewdness, their punishment is half that for free women. This (kind of marriage) is for those among you who fear falling into evil. But to have patience would be better for you, and Allah is Forgiving, Merciful."
Following the statements about marriage, this verse expresses the conditions of marrying she slaves whose dowries and expenses are usually lighter and easier. At first it says:
Then it adds that for recognizing their Faith, you are commissioned to hear their apparent expressions, and as for their innate thoughts and hidden secrets, it is so that Allah knows well of your faith.
And, in view of the fact that some men were not so willing to marry the slave maidens, in this verse the Qur'an remarks that all of you have come into being from only one couple, therefore, you must not dislike marrying them. It says:
Then, the Qur'an points to one of the conditions of this marriage. It is the permission of the concerning master, while without that permission the marriage is invalid. It says:
Next to this statement, it says:
It is understood from this sentence that an appropriate and worthy dowry should be assigned for them, and it must be given to them. It is also understood that their slaves can possess some wealth when they have lawfully obtained it.
One of the other conditions that this marriage has is that these maidens should be taken from among those who are chaste, not from among those who commit manifest lewdness.
In agreement with the ordinances stated upon marriage with slave maidens and supporting their rights, the holy verse continues the words about their punishment when they divert from the path of piety and chastity. It says:
This part of the holy verse means that they must be beaten only fifty stripes.
Then, it adds that this kind of marriage with such slave maidens is for those who are severely involved in the pressure of the sexual instinct and are not capable to marry free women.
Therefore, it is not admissible for men other than them.
But, next to that, it says that being patient and avoiding such sort of marriage, from the point of some ethical and social interests, is of your gain as far as you are able to restrain yourself and you do not fall into committing sin.
At the end of the verse, it remarks that upon what you have done before this, Allah is Forgiving, Merciful. It says: