means the remainder of food and drink. From the same root comes the word sāʾir, meaning “what remains.”

The evidence is the Prophet’s saying concerning the cat: “It is not impure; it is one of those that frequently move about among you, male and female alike.” (1)

He ruled that it is not impure. Purity and impurity are opposites; thus, it necessarily follows that it is pure, since there is nothing beyond impurity except purity.

His saying: “It is not impure; it is one of those that frequently move about among you, male and female alike.” (867)

A ṭawwāf is one who repeatedly comes and goes. From this comes circumambulation of the House, because a person repeatedly walks around it.

His statement, “and the leftover water of animals physically smaller than it is pure.” The evidence is analogy with the cat …

Analogy is the extension of the ruling of an established case to a subsidiary case on account of a common effective cause. Since the effective cause in the case of the cat is its frequent movement about among people, the ruling must be tied to that, for the Prophet did not give its small body size as the reason. Had he done so, we would have accepted it and made it the basis of the ruling. Thus, considering small body size to be the effective cause is incorrect, because it establishes an effective cause that the Lawgiver did not give, while disregarding an effective cause that the Lawgiver did give. The effective cause is its frequent movement about, and this is an appropriately relevant cause, namely the hardship of avoiding it. Therefore, the ruling must be tied to it.

Furthermore, if we wished to make a complete analogy, assuming that the effective cause were small body size, we would have to say: the leftover water of the cat, and whatever is like it in