Spinsters and Prostitutes
Allah, in the following verses, makes his views on spinsterhood, pre-marital sex, the emancipation of slaves and abstinence crystal clear. He is less forthcoming as to whether a man forcing a slave-girl into prostitution or who profits from his slaves prostituting themselves will face any sanctions from Allah.
24:32 Encourage the unmarried among you and the righteous among your servants and maids to marry. If they are poor, Allah will enrich them from His Bounty. Allah is All-Embracing, All-Knowing.
24:33 Let those who do not find the means to marry be abstinent, till Allah enriches them from his Bounty. Those whom your right hands own and who wish to pay for their emancipation, conclude a contract with them, if you know that there is some good in them, and give them of Allah’s wealth which He gave you. Do not force your slave-girls into prostitution, if they wish to be chaste, in order to seek the fleeting goods of this life. Whoever forces them, surely Allah, after their being forced, is Forgiving, Merciful.
24:34 And We have sent down to you signs making everything clear, and an example of those who have gone before you, and an exhortation to the God-fearing.
Prostitution, in the Koran, seems to be a matter of choice, for slave-girls anyway. The Prophet, for his part, did allow for temporary marriages so that men at war with no female captives to rape could still have sex. Except under extraordinary circumstances, Sunnis consider temporary marriages haram while Shiites have made it part of their legal code and accessible to just about everyone. A few hadiths on the subject of temporary marriages:
We used to participate in the holy wars carried on by the Prophet and we had no women (wives) with us. So we said (to the Prophet). "Shall we castrate ourselves?"
But the Prophet forbade us to do that and thenceforth he allowed us to marry a woman (temporarily) by giving her even a garment, and then he recited: "O you who believe! Do not make unlawful the good things which Allah has made lawful for you." Qur'an 5:87
Sabra Juhanni reported (unlike Bukhari, Sahih Muslim does not use quotation marks in his hadiths):
Allah's Messenger (may peace be upon him) permitted temporary marriage for us. So I and another person went out and saw a woman of Bana 'Amir, who was like a young long-necked she-camel. We presented ourselves to her (for contracting temporary marriage), whereupon she said: What dower would you give me?
I said: My cloak. And my companion also said: My cloak. And the cloak of-my companion was superior to my cloak, but I was younger than he. So when she looked at the cloak of my companion she liked it, and when she cast a glance at me I looked more attractive to her.
She then said: Well, you and your cloak are sufficient for me.
I remained with her for three nights, and then Allah's Messenger (may peace be upon him) said: He who has any such woman with whom he had contracted temporary marriage, he should let her off.
Sahih Muslim 8:3252