The Muslims are unanimous that selling wine is forbidden and that wine itself is impure—save for an isolated opinion that disputes its impurity. Likewise, carrion in all of its life-bearing parts, and the swine in every part of its body that can sustain life, are impure. The scholars disagreed, however, about benefiting from the pig’s hair: Ibn al-Qāsim allowed it, whereas Aṣbagh forbade it.

The second category comprises impure substances that necessity sometimes requires, such as animal dung (rajīʿ) and the manure used in orchards. Within the school there is disagreement over selling these: one view proscribes the transaction outright, another permits it without restriction, while a third differentiates between human excrement and manure—allowing the sale of manure but not of human waste.

They also differed over articles made from an elephant’s tusk, because they disagree about whether ivory is impure. Those who regard it as a tooth consider it carrion; those who see it as an inverted horn assign to it the ruling of horn. The issue remains disputed within the school.

Among things whose sale is prohibited, even though they are not impure—or whose impurity is itself disputed—are the dog and the cat. As for the dog, the jurists disagreed. Al-Shāfiʿī held that the sale of any dog is invalid, whereas Abū Ḥanīfah deemed it permissible. Mālikī scholars drew a distinction between a dog kept for livestock or crops—whose keeping is allowed—and a dog whose keeping is not permitted. They agreed that a dog one is not allowed to keep may not be sold for its use or possession. With respect to a dog sought for food, they also differed: whoever permits eating it allows its sale, while whoever—according to the report of Ibn Ḥabīb—does not permit eating it likewise forbids its sale. They further disagreed over the sale of dogs whose keeping is sanctioned: some declared it prohibited, others merely disliked.

Al-Shāfiʿī’s position rests on two points: first, the established ḥadīth of the Prophet—peace and blessings be upon him—prohibiting the price of a dog; and second, his view that the dog is intrinsically impure like the swine, as we have already demonstrated in the Book of Purification. Those who allow the sale argue that the dog is inherently pure and its flesh is not forbidden to eat; therefore its sale is lawful, just like any pure item. Their proofs for its physical purity were cited earlier in the Book of Purification, and their arguments for its permissibility as food appear in the Book of Dietary Laws.

Those who distinguish between different types of dogs base their view on the claim that, in principle, neither eating the dog nor benefiting from it is lawful, except for what the ḥadīth exempts—namely the shepherd’s dog, the farm dog, and the like. In addition, there are other, less well-known traditions in which this exemption is coupled with a prohibition