Book of Īlāʾ
Īlāʾ is the oath of a husband whose divorce is legally effective, by which he undertakes to withhold intercourse from his wife either absolutely or for more than four months. According to the later Shāfiʿī position, the oath need not be limited to swearing by Allah and His attributes: even if he links the abstention to a divorce, a manumission, or says, “If I have intercourse with you, I owe Allah a prayer, a fast, a pilgrimage, or a manumission,” he is nevertheless considered to have made īlāʾ.

If a third party makes such an oath, it is a mere oath; should he later marry the woman, no īlāʾ arises.
If the oath concerns a woman whose genital passage is blocked (ratqāʾ) or sealed (qarnāʾ), or the husband himself is castrated, the īlāʾ is invalid according to the authoritative view.
If he says, “By Allah, I will not have intercourse with you for four months; when they end, by Allah I will not have intercourse with you for another four months,” and he repeats this, he is not considered a mulwi on the soundest opinion.
But if he says, “By Allah, I will not have intercourse with you for five months; when they end, by Allah I will not have intercourse with you for one year,” two independent acts of īlāʾ are established, each subject to its own ruling.
Should he attach the oath to something highly unlikely to occur within four months—such as the descent of Jesus, peace be upon him—he becomes a mulwi; if he deems that event likely to occur within the four months, then he does not, and the same applies if he is merely uncertain, according to the preferred view.

His wording may be explicit or allusive. Explicit formulations include: “penetrating the vagina with the penis,” “intercourse,” “coitus,” and “deflowering a virgin.” According to the later position, terms like “touching,” “lying with,” “intimacy,” “approaching,” “covering,” “drawing near,” and the like are allusive.
If he says, “If I have intercourse with you, my slave is free,” and later loses ownership of the slave, the īlāʾ lapses.
If he says, “Then my slave is free as expiation for my ẓihār,” and he had previously pronounced ẓihār, he is a mulwi; otherwise there is neither genuine ẓihār nor genuine īlāʾ, though both are judged to exist outwardly.
If he says, “In expiation for my ẓihār, should I pronounce ẓihār,” he is not a mulwi until he actually utters ẓihār; whereas if he says, “If I have intercourse with you I will pronounce ẓihār against you,” he does become a mulwi. If he then has intercourse, the co-wife is divorced and the īlāʾ ends.
The stronger view is that if he says to his four wives, “By Allah, I will not have intercourse with any of you,” he is not deemed a mulwi in