His statement, “or a substantial amount”: the author leaves “substantial” unrestricted. The well-known principle is that whatever is mentioned without being defined by the Sacred Law is referred back to customary practice, as it is said:

Whatever is mentioned and not defined
by the Sacred Law—such as a protected place—define by customary practice. (1)

Thus, what counts as substantial is determined by people’s customary practice: if they say, “This is substantial,” then it is substantial; and if they say, “This is slight,” then it is slight.

Some scholars said that what matters is each individual’s own assessment. (2) Thus, whatever a person considers substantial is substantial, and whatever he considers slight is slight.

This view is open to criticism, because some people suffer from misgivings, so that even a single drop seems substantial to them; while others are careless, such that if a great deal of blood comes from them, they say, “This is slight.”

The sound view is the first: what counts is the judgment of ordinary people. Whatever they regard as substantial is substantial, and whatever they regard as slight is slight.

His statement, “impure matter other than these two”: “impure” excludes what is pure. Thus, if something pure emerges from the rest of the body, even in a substantial amount, it does not invalidate ablution, such as sweat, saliva, and tears....

His statement, “other than these two,” means other than urine and feces. This therefore includes blood, vomit, blood from wounds, wound discharge, and everything that may emerge which is not pure.