It is important that one looks at the verses which show that there is an encouragement for the concubines to be married. Then, one can look at the counterargument. However, we will analyze the verses and observe the broader picture about the encouragement towards getting the female slaves married.
There are several verses in the Quran that mentions the marriage of concubines. The Quran stated, “If you fear that you will not deal fairly with orphan girls, you may marry whichever (other) women seem good to you, two, three, or four.” Quran [4:3]
However, the same verse states, “If you fear that you cannot be equitable (to them), then marry only one, or your slave(s): That is more likely to make you avoid bias.” Quran [4:3]
This is widely interpreted to mean that in addition to the four wives which the Muslims have placed as the upper limit, based on their interpretation of this verse, a man could have several concubines, unspecified. Muhammad Asad published his book called “The Message of the Quran.” According to his translation and commentary on the Quran in English, he has pointed out something that is often overlooked.
The verse says, "If you fear that you will not do justice to the orphans, marry those women who are suitable for you in twos and threes and fours. But if you fear that you will not do justice, then only one, meaning marry only one. Or what your right hands possess." At this point, the Muslim interpreters would insert the thought that "or" remains satisfied with "what your right hands possess."
Yet, Muhammad Asad needs to assume the grammatical continuity of the verse. It says, "If you fear you will not do justice, then marry the women who are suitable for you in twos and threes and fours, and if you fear even then that you will not do justice, then marry only one, or marry what your right hands possess." This leads to the understanding that the Muslim community did go to war with others. At that time, there wasn’t the Geneva Convention and other conventions for the humane treatment of prisoners of war. How were the prisoners of war to be dealt with at that time? The prisoners of war were allocated as domesticated servants within the society.
They were kind of integrated into society. In fact, several men rose to positions of power, even while they were servants within the community. They had been captives of war, but they rose to prominence as teachers and Quranic memorizers. The sons born to these women would rise to prominence because this was a man's world. Women did not have so much of opportunities to excel and become leaders in this society. Nonetheless, in that society, women were allocated as servants along with men, it was assumed by Muslim scholars that if a man owned a woman in that circumstance, he has the automatic right to sleep with her.
However, this Quranic verse is indicating that if one has such a woman in one’s possession, then marry her, because the verb that says marry in twos and threes and fours, and then if you fear you will not do justice, then only one, the verb is implied. Then only one, it doesn't say marry only one. However, everybody understands that it means marry only one. The verb marry is extended to that object, the one. Yet, the same verb must extend to what follows. “Marry one, meaning from among the free women, or whoever your right hands possess.” It could be multiple.
Why would the Quran limit the men to four wives at one time, but give them the permission to marry an unlimited number of concubines? A good explanation for that is what does one do with the female slaves? If one leaves them, they are separated from their families and from their husbands, if they had husbands prior to their being captured. If they are left single in this new society, in that situation, when women did not have the kinds of protection that women can be presumed to have nowadays. This is the case since modern laws protect the rights of women. Consequently, women may have become in that situation, being in that vulnerable state, targets for abuse by other men who would see them as being unmarried. From their perspective, the sickness is in their hearts. As the Quran describes some men might target these women. If the women are known to be married to their masters, then that would give them protection. That would mean that the Quranic word “Mohsin,” which is used in reference to married women in general, would now apply to them in particular. Mohsin in Arabic means something that is fortified, protected. That would be the reason.
If we assume that the Quran limits the number of wives to four. This has been a common interpretation, but the Quranic verse does not have that limitation. However, I'm comfortable with that interpretation as the Muslim scholars who reached that interpretation imagined, that it would be very difficult for a man to care for so many women all at once. Despite it being a difficult task, it is allowed in the law. It's not an ideal situation, but sometimes it is not necessary to make a law. That thing would naturally pan out. In addition, the number of men and women in societies has generally remained roughly equal, one can assume that in most situations, one man would be married to one woman because that would be the natural pairing off. That would be the balancing of the male and female populations.
There are other verses that refer to marriage. In surah 4 verse 23 of the Quran states, “You are forbidden to take as wives, your mothers, daughters, sisters, paternal and maternal aunts, the daughters of brothers and daughters of sisters, your milk-mothers and milk-sisters, your wives’ mothers, the stepdaughter in your care—those born of women with whom you have consummated marriage.” Quran [4:23]
The Quran also states, “Also forbidden are women already married, other than your slaves. God has ordained all this for you.” Quran [4:24]
One can assume that some women who were previously married were captured in war. As a result, they're possessions of the Muslim community. What's to be done? Can you marry them? This verse says, “Other women are lawful to you, so long as you seek them in marriage, with gifts from your property, looking for wedlock rather than fornication.” Quran [4:24].
These are the two categories. This category says, if the women are previously married, you cannot marry them now, but if they have been captured in war, you can seek them, as well as unmarried women, with your wealth. Meaning, just as a man would go propose to a woman today by buying her a nice diamond ring, the custom at the time was that women generally did not own much property and did not have much opportunity or earnings of their own. It’s a good way to start the marriage would be as part of the marriage proposal and give a dower.
The Quran is saying, “Make this offer to the single women, but the women who are the right-hand possessions, meaning the captives of war in that situation. Well, that was one of the categories. People have been owned through a variety of other means. Yet, the Islamic ethos said that we're not going take free persons and make them into slaves. In fact, this became forbidden in Islamic society.
The only avenue open for the new supply of slaves was through the war situation in which captives were brought into society. If a female captive was brought, she should be sought in marriage by offering her a dower. It may be less, and maybe her freedom would be considered the dower itself. Nevertheless, the Quran is prescribing marriage. In the following verse number 25 in the same surah, it goes into more detail about a man marrying a female captive of war.
The implication of these verses on marriage is that it's good for the female slaves instead of them being turned into concubines. Rather, they could be married off and be wives within the society. Also, one could have mentioned surah two, verses 221, and surah 24, verse 32.
To conclude, the Quran is telling men to marry off those women who are there in their possession, either to someone else or as an alternative, they could have married the slave women themselves. Rather than just simply assume that they have the automatic right to sleep with them. Seeing that general picture, one can now look at the flip side. If some people are thinking they're seeing verses in the Quran which indicate that a man has the automatic right to sleep with his slave girl, to take her on as a concubine, and to treat her like his lawfully wedded wife.