Is it permissible to marry the sister of a female slave one has had intercourse with?
Chapter on What is Prohibited to Marry and Combining Between Them and Other Matters
Al-Mughni
Book of Marriage
Primary text
There are differing views on the validity of marrying the sister of one's own female slave after intercourse. One opinion, attributed to Imam Ahmad and one narration from Malik, holds that the marriage is invalid. This ruling is based on the concept that the slave becomes an established sexual partner (firasht - a place/status established for intercourse), and it is impermissible to establish a second, concurrent sexual status with her sister, similar to how one cannot simultaneously have intercourse with both sisters. Furthermore, the act with the sister (the slave) conflicts with the permissibility of marrying the other sister who is already established for that purpose, which invalidates the subsequent marriage contract.
Supporting text
An alternative view, held by Abu Hanifa and considered the apparent meaning by some scholars, suggests the marriage contract itself is valid, but the previously owned slave remains unlawful for the master until the sister is divorced or the impediment is removed. Another opinion states that the marriage is valid, and the previously owned slave becomes lawful for him while the sister becomes unlawful, based on the principle that marriage is a stronger bond than ownership rights for sexual relations, necessitating the precedence of the stronger contract. Opponents argue against the supposed strength of marriage over ownership intercourse, pointing out that prior sexual contact (like intercourse with the slave) prevents marrying her daughter or mother, making the current situation analogous to marrying a woman during her sister's waiting period due to lack of *Istibra'* (seeking purity of the womb).