What is the ruling when an oath to perform an act is followed by an exception regarding the will of another person?
General Chapter
Al-Mughni
Book of Oaths
Primary text
If a person swears, "By Allah, I will drink, unless Zayd wills that I do not drink," he has obligated himself to drink unless Zayd wills that he refrain from drinking. This is because the exception is the opposite of the excepted matter, and the excepted matter is the obligation of drinking by his oath. If he drinks before Zayd's will is known, he is absolved. If Zayd states, 'I have willed that you not drink,' the oath is dissolved because it was contingent upon his will not to drink, and since that condition was not preceded by the opposite will, its condition was not met.
Supporting text
If Zayd states, 'I have willed that you drink,' or 'I did not will that you not drink,' the oath is not dissolved because this expressed will is not the exception stipulated. If Zayd's will is hidden, drinking becomes obligatory because the obligation to drink was linked to the absence of the refraining will, which is presumed absent based on the original state.