Let us now see what the Qur’an says after allowing up to four wives. It says, “But if you fear that you will not maintain equity then (keep to) one woman, or a bondwoman you own.” [4:03]
From here we find out that having more than one wife is permissible and appropriate only on condition that equality can be maintained among all wives as required under the Shariah of Islam and that the right of all can be duly fulfilled. If one does not have the capability to discharge his obligations in this manner, the rule is to keep to only one wife. As stated earlier, the injustice of multiple marriages during Jahiliyyah without any considerations of rights of wives had made a mockery of this relationship.
So, the Quranic command was: if you are unable to do perfect justice between wives, then restrict yourself to no more than one, or make do with a bondwoman you may own. At this point, please keep in mind that bondwoman has very special conditions under which such possession becomes possible, conditions which generally do not exist these days. Therefore, the act of starting to live with someone out of wedlock and declaring her a bondwoman as something allowed by Shariah is unlawful and haraam.
While Quran has allowed having four wives, it is obligatory to maintain justice and equality between them. Anyone who thinks of having more than one wife should first think about all those factors and conditions around him. He must introspect, weigh, deliberate and figure out realistically whether or not he has the ability or the capability or quality to treat all of them equally and justly without causing any infringement of their rights. If strong likelihood exists that one will not be able to come up to the standard and most probably will fail to maintain such justice and equality then having the audacity to go ahead and step into the bonds of more than one marriage is a really a thoughtless plunge into a grave sin. Any infringement of a wife’s rights can be challenged in an Islamic Court and the aggrieved wife can receive redress from there.
The Prophet has laid great emphasis on maintaining full equality and justice between all wives and he has given stern warnings against those who do otherwise. Above all, he has demonstrated the desirable ideal through his own conduct, reaching the outer limits of treating his wives equally even in matters in which equality is not mandatory.
In a hadith, the Prophet has said, “Anyone who has two wives and he cannot fulfill their rights equally and justly, shall be raised on the Day of Doom in a condition that one of his shoulders will be drooping down.” [Mishkat, p. 278]
We should, however, keep in mind that this equality of treatment is necessary in things which are within the control of man. For example, the coverage of personal expenses and parity in overnight stays. As for things out of man’s control, such as natural inclination of his heart which might tilt towards one of them, there is no accountability there for this is not a matter of choice. However, the binding condition is that this tilt should not affect matters which are within man’s control. Our Prophet treated his wives with full equality in everything within his control, yet he pleaded with his Lord, “O Allah, this is my equalization in what I control. So, do not hold me accountable in matters You control and I do not.”
Obviously, something even an infallible Messenger is not able to do, how can someone else claim to have the ability to do it? Therefore, in another ayah of the Qur’an this matter out of man’s control has been mentioned in the following words, “And you shall be unable to maintain perfect equality between the women.” [4:129]
Here, it has been made clear that love and the tilt of the heart are something out of man’s control. It is beyond man’s power to achieve perfect equality of treatment in what comes from the territory of the heart. If you love one of your wives more than the other, there is nothing you can do without it. But total indifference and heedlessness towards the other wife is not permissible even under this situation.