Forced Prostitution

وَلْيَسْتَعْفِفِ الَّذِينَ لَا يَجِدُونَ نِكَاحًا حَتَّىٰ يُغْنِيَهُمُ اللَّهُ مِن فَضْلِهِ

 وَالَّذِينَ يَبْتَغُونَ الْكِتَابَ مِمَّا مَلَكَتْ أَيْمَانُكُمْ فَكَاتِبُوهُمْ إِنْ عَلِمْتُمْ فِيهِمْ خَيْرًا وَآتُوهُم مِّن مَّالِ اللَّهِ الَّذِي آتَاكُمْ 

وَلَا تُكْرِهُوا فَتَيَاتِكُمْ عَلَى الْبِغَاءِ إِنْ أَرَدْنَ تَحَصُّنًا لِّتَبْتَغُوا عَرَضَ الْحَيَاةِ الدُّنْيَا

 وَمَن يُكْرِههُّنَّ 
فَإِنَّ اللَّهَ مِن بَعْدِ إِكْرَاهِهِنَّ غَفُورٌ رَّحِيمٌ

And let those who do not find the means to marry keep chaste until Allah makes them free from want out of His grace.
And (as for) those who ask for a writing from among those whom your right hands possess, give them the writing if you know any good in them, and give them of the wealth of Allah which He has given you;
and do not compel your slave girls to prostitution, when they desire to keep chaste, in order to seek the frail good of this world's life; 
and whoever compels them, 
then surely after their compulsion Allah is Forgiving, Merciful.

[Al-Quran, an-Nur 24:33, Translator: Shakir] 

Surah an-Nur begins with the declaration that this surah is obligatory, and the ayaat clearly detailed (Q24:1). The next few ayaat clearly list the punishments and code of conduct in cases of adultery. Yet, not all cases of adultery are voluntary. There are many women, enslaved, even in today's world, who are forced into prostitution by their owners. Allah knows it and offers clear hope to such women who are oppressed and forced into such sinful activities!  

The prostitution industry flourishes due to men willing to pay for sexual favours. Q24:33 begins with the directive to unmarried men to keep themselves chaste till they can afford to get married. Elsewhere in The Quran, men are repeatedly exhorted to pay the bridal due when solemnising a marriage (free women: Q4:24, slave women: Q4:25, women of The People of The Book: Q5:5, the Prophet's to-be-wives: Q33:50, female emigrants who have embraced Islam: Q60:10). The only exception to the rule seems to be where permission is granted to marry widows (mothers of orphans) for the sake of the orphans' welfare, and even in such situations the directive is to pay graciously; however the women may remit as per their peculiar situation (Q4:2-6 , Q4:127).  

Men have been made protectors of women and are responsible for the financial needs of their women (Q4:34).  

Some people argue that payment of bridal due is similar to payment of money to a prostitute. Allah has forbidden sexual relations outside the bond of marriage, and he has enjoined marriage: 

وَأَنكِحُوا الْأَيَامَىٰ مِنكُمْ وَالصَّالِحِينَ مِنْ عِبَادِكُمْ وَإِمَائِكُمْ إِن يَكُونُوا فُقَرَاءَ يُغْنِهِمُ اللَّهُ مِن فَضْلِهِ وَاللَّهُ وَاسِعٌ عَلِيمٌ

And marry the single among you and the righteous among your male slaves, and your female slaves. If they are poor, Allah will enrich them from His Bounty. And Allah (is) All-Encompassing, All-Knowing. 

[Al-Quran, an-Nur, 24:32]

And Allah knows best!