﴿ ٱلزَّانِى لَا يَنكِحُ إِلَّا زَانِيَةً أَوْ مُشْرِكَةًۭ وَٱلزَّانِيَةُ لَا يَنكِحُهَآ إِلَّا زَانٍ أَوْ مُشْرِكٌۭ ۚ وَحُرِّمَ ذَٰلِكَ عَلَى ٱلْمُؤْمِنِينَ ﴾

“[Both are equally guilty:] the adulterer couples with none other than an adulteress - that is, a woman who accords [to her own lust] a place side by side with God; and with the adulteress couples none other than an adulterer - that is, a man who accords [to his own lust] a place side by side with God: and this is forbidden unto the believers.”

(The adulterer) from the people of the Book who admits his crime (shall not marry save an adulteress) from the slaves of the people of the Book (or an idolatress) from the slaves of the Arab idolaters, (and the adulteress none shall marry save an adulterer) from the people of the Book (or an idolater) from the Arab idolaters. (All that) marrying the slaves of the people of the Book and the slaves of Arab idolaters (is forbidden unto believers) this verse was revealed about a group among the Companions of the Prophet (pbuh) who wanted to marry some slaves from the people of the Book and Arab idolaters in Medina. These slaves were known adulteresses but these prophetic Companions wanted to marry them in order to win them over. When this verse was revealed they refrained from marrying them.