Overall meaning :
The Almighty proclaims that it is forbidden for men to marry women who are already married except those who have fallen into their possession in their war against the unbelievers. With these they can have intimate relations even if they are married but after waiting the period for the passing of one menstruation. The women He has listed in these as forbidden to marry, He states, is His command which is binding on the faithful, explaining that all women other than these are lawful for the believers to marry provided that they seek them with their wealth—either by taking them in marriage by paying them the agreed dowries, thereby desiring to preserve their chastity, or by purchasing female slaves through legal means for fear of committing adultery. And they must give the bridal-due (dowry) as a duty to whomever of them they consummate the marriage with under these conditions. Spouses will incur no sin if, after having agreed upon this lawful due, they freely agree with one another upon anything else, such as decreasing or increasing the amount of the dowry, delaying its payment or granting the husband exemption from paying it. Surely Allah is All-Knowing, All-Wise.
He further teaches that those who cannot afford to marry free believing women may marry believing women that have fallen into believers’ hands as slaves, stating that He knows best those among them who truly believe and that they are all descendants of Adam and are all equal as human beings in His sight. Therefore, they should not disdain to marry slaves, when necessary, with their guardians’ permission and they must give them their dowry—which Allah has prescribed for them—in full and without delay, provided that they are chaste, avoid loose conduct, neither commit fornication openly, nor take secret paramours. If after marriage they commit adultery, they will have to suffer half the penalty inflicted upon free women before marriage; that is, to be whipped fifty lashes. Such provision to marry believing slave women when unable to marry free women is for those who fear they may commit fornication, but to abstain from marrying slave women while remaining chaste until they can afford to marry free women, Allah teaches, would be better for them. Allah is All-Forgiving, All-Merciful.