Does consuming food when the purchase involved a specific half or the acquisition of the remaining half after an initial purchase break an oath sworn regarding the purchase by Zayd?
General Chapter
Al-Mughni
Book of Expiations
Primary text
If one purchased half of the food in an undivided share (musha'), or purchased one half and then purchased the remaining half and consumed from it, the oath is broken. The ruling on this is subject to the preceding difference of opinion. If Zayd purchased a defined half, mixed it with the other half, and consumed all or more than half, the oath is broken without dispute because the person consumed from what Zayd certainly purchased.
Supporting text
If the person consumed exactly half, or less than half, there are two views: one holds the oath is broken due to the common expectation that what Zayd purchased cannot be isolated, making the breaking of the oath strongly apparent. The second view holds the oath is not broken because the default is non-breach, and it is not certain that the consumed portion was specifically what Zayd purchased.