Is human spittle, tears, sweat, mucus, and phlegm pure or impure?
Chapter on Praying with Impurity and Other Matters
Al-Mughni
Book of Prayer
Primary text
Human spittle, tears, sweat, mucus, and phlegm are pure. Evidence for the purity of spittle is found in the incident on the Day of Hudaybiyyah, where the Prophet (peace be upon him) spat into a man's palm, and the man wiped his face with it, which would not have been done had it been impure. Furthermore, concerning spitting indoors, the Prophet (peace be upon him) instructed that if one must spit, it should be to the left, under the foot, or by spitting into one's garment and wiping it together, implying the resulting substance is pure enough for such handling, even during prayer. This purity extends to phlegm originating from the chest, similar to mucus from the head. This is the position held by Abu Hanifa and supported by the generalization derived from the aforementioned hadiths.
Supporting text
Al-Qadi held that phlegm is impure because it is transformed food originating in the stomach, similar to vomit. However, the primary position counters this by arguing phlegm is formed from vapors, like what descends from the head, and it is difficult to guard against, thus resembling mucus.