What is the ruling on violating an oath by consuming part of something specified?
General Chapter
Al-Mughni
Book of Expiations
Primary text
If one swears not to drink the water in a specific vessel and drinks part of it, there are two narrations regarding whether this constitutes violating the oath. However, if one swears not to drink the water of the Tigris River (Dajla) or the water of this specific river, violating the oath occurs upon drinking the smallest portion, because drinking the entirety is impossible outside of the oath's specification. Therefore, the oath applies to restraining oneself from what is possible to do, which is drinking a portion, similar to an absolute oath 'I shall not drink water.' Abu Hanifa holds this view.
Supporting text
The companions of Al-Shafi'i state that if the oath concerns a genus, such as people, water, bread, or dates, violating the oath occurs by performing part. If the oath encompasses all individuals, such as Muslims, polytheists, or the needy, the oath is not violated by performing part. If the oath concerns a qualified genus name, like the water of the river or the water of the Tigris, there are two opinions.