“Today is the slave market day. Today is the day where this verse applies: ‘Except with their wives and the (captives) whom their right hands possess,- for (then) they are not to be blamed.'”
That’s Qur’an 23:6. The whole passage is: “The believers must (eventually) win through, those who humble themselves in their prayers; who avoid vain talk; who are active in deeds of charity; who abstain from sex, except with those joined to them in the marriage bond, or (the captives) whom their right hands possess, for (in their case) they are free from blame.” (Qur’an 23:1-6)
According to Islamic law, Muslim men can take “captives of the right hand” (Qur’an 4:3, 4:24, 33:50). The Qur’an says: “O Prophet! Lo! We have made lawful unto thee thy wives unto whom thou hast paid their dowries, and those whom thy right hand possesseth of those whom Allah hath given thee as spoils of war” (33:50). 4:3 and 4:24 extend this privilege to Muslim men in general.
The rape of captive women is also sanctioned in Islamic tradition:
Abu Sirma said to Abu Sa’id al Khadri (Allah he pleased with him): 0 Abu Sa’id, did you hear Allah’s Messenger (may peace be upon him) mentioning al-’azl? He said: Yes, and added: We went out with Allah’s Messenger (may peace be upon him) on the expedition to the Bi’l-Mustaliq and took captive some excellent Arab women; and we desired them, for we were suffering from the absence of our wives, (but at the same time) we also desired ransom for them. So we decided to have sexual intercourse with them but by observing ‘azl (Withdrawing the male sexual organ before emission of semen to avoid conception). But we said: We are doing an act whereas Allah’s Messenger is amongst us; why not ask him? So we asked Allah’s Messenger (may peace be upon him), and he said: It does not matter if you do not do it, for every soul that is to be born up to the Day of Resurrection will be born. (Muslim 3371)