Is one liable for breaking an oath not to drink from the Euphrates river if they drink from a stream drawing water from it?
General Chapter
Al-Mughni
Book of Expiations
Primary text
If one swears not to drink from the water of the Euphrates and then drinks from a river taking water from it, the oath is broken (Hanith). This is because the essence of drinking from it is drinking from its water, making the oath broken, similar to swearing not to drink from its specific water. This is one of the two established views among the companions of Al-Shafi'i.
Supporting text
The second view holds that the oath is not broken. This is the position of Abu Hanifa and his companions, except for Abu Yusuf, who has a narration stating the oath is broken. The reasoning for non-breaking is that the water taken by the secondary river is attributed to that river, not the Euphrates, thereby removing its attribution to the Euphrates.