Women of the Book and Slave-Girls
Muslim women are not allowed to marry outside the faith but Muslim men are allowed to do so, as long as they marry Women of the Book – Jews, Christians and members of a religious sect called Sabians.
5:5 This day the good things have been made lawful to you; the food of the People of the Book is lawful to you, and your food is lawful to them; and so are the believing women who are chaste, and the chaste women of those who were given the Book before you, provided you give them their dowries and take them in marriage, not in fornication or as mistresses. If any one denies the faith, his work shall be of no avail to him, and in the Hereafter he will rank with the losers.
As you can appreciate, this last revelation expanded many-folds the available stock of virgins that a believing man could choose from. And if this still was not enough to satisfy your sexual appetite, or discriminating taste, or you could not afford a believing woman, you could always take wives from among your believing slave-girls.
4:25 Whoever of you cannot afford to marry a free, believing woman, let him choose from whatever your right hands possess (captives of war or slave-girls) of believing girls. Allah knows best your faith; you come one from the other. So marry them with their parents’ leave and give them their dowry honourably, as chaste women, neither committing adultery nor taking lovers …
The pain a former slave-girl can expect if she cheats on her husband with another man, must take into account her previous status as a man’s right hand possession.
4:25 … If they are legally married and commit adultery, their punishment shall be half that of a free women. Such is the law for those of you who fear committing sin; but to abstain is better for you. Allah is All-Forgiving and Merciful!
Why all the rules about the women and girls a man can marry? It’s a question of lust and Allah’s Mercy.
4:26 Allah wants to explain to you [His laws] and to guide you along the paths of those who preceded you, and to be Merciful to you. Allah is All-Knowing, Wise!
4:27 Allah also wants to be Merciful to you, but those who follow their lust want you to deviate greatly from the right course.
Some must have found revelation 4:27 somewhat amusing coming from a man with a penchant for beautiful girls as young as nine years old e.g. Aisha, with fourteen official wives, one of which was previously married to his adopted son Zayd but whom he just had to have after seeing her almost naked, and an undisclosed number of concubines and slaves girls.
4:28 Allah wishes to lighten your burden; for man was created weak.