Must the object of the oath (Ila') be a wife for the oath to constitute Ila'?
General Chapter
Al-Mughni
Book of the Oath of Abstention (Ila')
Primary text
The object upon which an oath of Ila' (swearing to abstain from sexual intercourse) is taken must be a wife. This is established by the decree of God, "For those who swear off relations with their wives, there is a waiting period of four months" (Quran 2:226). Furthermore, a non-wife has no right to sexual intercourse from the person, thus no Ila' can be sworn against her, just as with a strange woman. If a man swears not to have intercourse with his female slave, he is not considered to have performed Ila'. Similarly, if he swears not to have intercourse with a strange woman and subsequently marries her, he is not considered to have performed Ila'. This view is held by Al-Shafi'i, Ishaq, Abu Thawr, and Ibn al-Mundhir.
Supporting text
Imam Malik holds that the oath becomes Ila' if more than four months of the oath's duration remain, because the man is abstaining from intercourse with his wife due to his oath for the duration of Ila', thus becoming a Muuli. A narration from the Ashab al-Ra'y states that if a man swears not to approach a specific woman upon whom he currently has no marital claim, and later marries her, he does not become a Muuli. However, if he says, "If I marry so-and-so, by God I will not approach her," he becomes a Muuli because he tied the oath to the state of marriage, resembling the case where the oath is sworn after marriage.