Does an oath to abstain from intercourse until the wife wills it constitute Ila' (oath of abstinence)?
General Chapter
Al-Mughni
Book of the Oath of Abstention (Ila')
Primary text
If a husband swears, "By Allah, I will not approach you unless you will it" (W'allahi la wat'tuka in sha'a fulan), he does not become a Muli (one who has taken the oath of Ila') until she actually wills it, at which point the oath takes effect. This view is held by Al-Shafi'i, Abu Thawr, and the People of Opinion (Ashab al-Ra'y). The reasoning is that he only refrains from intercourse contingent upon her will, thus the Ila' is only established upon the occurrence of that will. If he says, "By Allah, I will not approach you if you will," the same ruling applies.
Supporting text
Some companions of Al-Shafi'i state that if the wife expresses her will immediately following his statement, the oath becomes binding. If she delays expressing her will, the oath is dissolved because the condition (her will) is considered an option granted to her, requiring immediate exercise, similar to the option granted in divorce ('Ikhtiyar fi al-talaq'). The prevailing view holds that because the oath is suspended upon the condition of willing using the particle 'in' (if), it remains suspended (Tarakhi) until the will is exercised, like other conditional stipulations.