He was also asked:

About a sick person for whom medicine was prepared by boiling, who then found mouse droppings in it.

He replied:

There is a well-known disagreement among the scholars on this issue: is a small amount of mouse droppings excused? According to one of the two views within the schools of Ahmad, Abū Hanīfah, and others, a small amount is excused, so the medicine mentioned may be consumed. This is the stronger of the two views. And Allah knows best.

He—may Allah have mercy on him—also said:

To proceed:

We were gathered to deepen our understanding of the religion and examine the grounds of the rulings prescribed by the Sharia—clarifying their scope, establishing them, setting out their foundations, and elaborating their details. The discussion turned to explaining the ruling on semen from humans and other ritually pure animals, and on the dung of livestock lawful to eat: are these pure or impure? Our companions wished to have the discussion recorded, allowing for some additions or omissions, so I wrote the following for them. I say—and there is no power nor might except through Allah:

This discussion is built around a foundational principle and two sections.

As for the foundational principle: