What is the legal consequence regarding affinity arising from intercourse under suspicion (watu' bil-shubhah)?
Chapter on What is Prohibited to Marry and Combining Between Them and Other Matters
Al-Mughni
Book of Marriage
Primary text
Intercourse under suspicion, whether in a void marriage or void purchase, establishes the prohibition of affinity (tahrim) concerning the man's father, son, grandfathers, and grandchildren. This is the established position of Malik, Al-Awza'i, Al-Thawri, Al-Shafi'i, Ahmad, Ishaq, Abu Thawr, and the Ashab al-Ra'y (Hanafi jurists). The evidence is that this type of intercourse is one where paternity (nasab) can be established, thus it establishes the prohibition of affinity, just as lawful intercourse does.
Supporting text
Intercourse under suspicion does not make the man permanently forbidden to marry women who were already forbidden to him by lineage (mahramiyyah), nor does it permit him to look upon the woman (ibahah al-nazar). This is because the intercourse itself is not lawful (mubah), and the prohibition of affinity relates to the perfection of the lawfulness of the act, which requires permissibility (ibahah). Furthermore, since looking upon the woman herself was not permitted, looking upon others related to her is certainly not permitted.