Islam, which commanded that marriages should be restricted to four, has, however, not imposed any restriction on the number of woman-slaves who may be kept in one's possession. This means thata man may keep as many slave-women as he likes under him. Why did Islam allow this?
Slaves comes into the possession of the master in three ways. These ways are: as inheritance, personal purchase and as captured prisoners-of-war. Of these three, a man can decide the number of slaves to be under him only in the case of personal purchase. He is, however, unable to control, or limit, the number of slaves who come into his possession by way of inheritance and as prisoners-of-war who are captured and enslaved. If the governments decision is to enslave the captured prisoners-of-war, the usual practice is to divide them amongst all those who participated in the war. In the event that a large number of prisoners-of-war are captured, then the number of slaves who come into the possession of each individual will increase. It may be seen from history that nearly six thousand men were captured in the Battle of Hunain.
The prisoners-of-war who were captured were, however, made slaves only under inevitable circumstances . The Muslims were not in the habit of capturing women and children when, in battle, the enemies were defeated at their hands. It may be seen that during the wars that took place in the time of the Caliphs, nobody was enslaved in Syria, Palestine, Iraq and Egypt. If in war, the men were killed or taken as prisoners, the women and children will, as a result, become orphans. Islam has commanded that they are never to be killed in war. Even if the children and women who went to war with their men are captured as prisoners, more often than not they were exchanged for Muslim prisoners. However, in some instances, Islam did permit their enslavement. It will be remembered that this permission was granted in a society in which slavery was prevalent.
In any case, to limit the number of slaves who came into one's possession, by these means under the existing circumstances was quite impractical. This was so in the case of slave women also. The question here is what could be done with the slaves that come into one's possession through various ways. They could be married off, indeed, but to find suitors for slave women is not an easy task. If they are married to male slaves who are in his possession, the children that they beget will belong to the master. It is only natural that the children of slaves have no option but to be the possession of the master who is the owner of their parents.
This meant that they, too, would end up being slaves. Apart from either option, they may be unconditionally set free. But such freedom will lead to their being rendered orphans, and to a serious erosion of values as well. Another option will be to allow her the exercise of all her human rights without yet marrying her and to let her live with her master. (After all, it would not be practical for all masters to set her free and then to marry her). The number of slaves living in such wise is limited, the question arises as to what is to be done with the other slave women who come beyond this limit but are still staying with the master. There would then be no means for them to attain their freedom. Their sexuality will then be either neglected or exploited. This will thus become the cause of great moral degeneration.
If these problems are seen in the context of a society in which slavery is in existence, the fact that the laws envisioned by Islam in the matter are, indeed, very practical ones will become clearly manifested. In such a society, it is not possible to fix a limit for the number of male slaves who will come into one's possession. This is also the case with slave women as well. Such restrictions are never practical in such a society. It was for the same reason that Islam never took the trouble to impose them.