Is the water separated from a non-Muslim woman's menses washing (Ghusl) purifying?
Chapter on what purification is achieved with regarding water
Al-Mughni
Book of Purification
Primary text
There is a difference of opinion regarding the water separated from a non-Muslim woman's menses washing. One narration holds that it is purifying because it did not remove an impediment to prayer, thus resembling water used for cooling down.
Supporting text
The alternative narration states it is not purifying because it removed the impediment to her husband's intimacy (Watu'), resembling the case of a Muslim woman washing with it. However, if she washes with it from Janaabah, it is uniformly considered purifying because it removed no impediment to prayer and was not used in an act of worship, similar to cooling water. Yet, another view suggests it should be prohibited because it was used for washing from Janaabah, akin to a Muslim woman washing with it.