Does illicit sexual intercourse (Zina) establish the prohibition of affinity (Muharramat)?
Chapter on What is Prohibited to Marry and Combining Between Them and Other Matters
Al-Mughni
Book of Marriage
Primary text
Illicit sexual intercourse with a woman establishes the prohibition of affinity such that she becomes forbidden to his father and son, and her mother and daughter become forbidden to him, just as if the intercourse had occurred through legal means or mistaken belief (*shubha*). This is the narration stated by Ahmad upon the authority of a group, and similar reports exist from 'Imran bin Husayn, al-Hasan, 'Atā', Tawus, Mujahid, al-Sha'bi, al-Nakha'i, al-Thawri, Ishaq, and the Companions of Opinion. This is supported by the verse: "And do not marry those whom your fathers married from women" (Quran 4:22), as sexual intercourse is referred to as marriage (Nikah) in poetry and contextually implied by the severity mentioned in the following verse (Quran 4:22), which applies primarily to sexual intercourse. Furthermore, a reported Hadith states that Allah does not look at a man who looks at the private parts of a woman and her daughter.
Supporting text
Ibn 'Abbas reported that unlawful intercourse does not establish prohibition, a view held by Sa'id bin al-Musayyib, Yahya bin Ya'mur, 'Urwah, al-Zuhri, Malik, al-Shafi'i, Abu Thawr, and Ibn al-Mundhir. Their evidence is the reported Hadith: 'What is unlawful does not make what is lawful unlawful' (La yuharrimu al-haramu al-halal), and because it is intercourse that does not render the woman legally established as a wife (*firash*), similar to the intercourse with a minor girl, which is prohibited but does not establish the ruling. They argue that the Hadith cited against them is not authenticated, being attributed to Ibn Ashwa' and some Iraqi judges, according to Imam Ahmad.