What is the ruling when a man loses ownership of a woman he has had intercourse with, then marries her sister, and subsequently regains ownership of the first woman?
Chapter on What is Prohibited to Marry and Combining Between Them and Other Matters
Al-Mughni
Book of Marriage
Primary text
If a man loses ownership of a woman with whom he has had intercourse (*al-mawtu'ah*), marries her sister, and then the first woman returns to his ownership, he is prohibited from having intercourse with either woman until the other is rendered unlawful to him through divestment of ownership or marriage. This is the explicit position stated by Ahmad. The reasoning is that when the first woman returned, she became conjugal property (*firash*), and since the first was also conjugal property, each one prohibits the other, similar to if she were alone with him.
Supporting text
The companions of Al-Shafi'i hold that neither woman becomes prohibited to him because the first one (whose ownership was regained) no longer retains the status of conjugal property (*firash*). This situation is analogous to one where a man has intercourse with a female slave and subsequently purchases her sister.