His statement: “Milk and wool in exchange for a sheep that has milk and wool.” According to the well-known position of the madhhab, milk and wool are subject to riba, for milk is sold by measure and wool by weight. Milk is measured because it is a liquid, while wool is weighed because it cannot be measured by volume. Thus, if one sells milk and wool for a sheep that has milk and wool, this is permissible.

It should not be said that this falls under the case of “a mudd (a standard measure) of ʿajwah dates and a dirham,” because he has sold one riba-bearing commodity for another, with something of a different kind accompanying one of them. No one would make such a claim. In the exchange of milk and wool for a sheep containing milk and wool, which side contains the excess?

The answer is: the sheep, since it includes additional meat, fat, bones, and so forth. Therefore, no one can claim that this is analogous to the case of “a mudd of ʿajwah dates and a dirham,” and thus invalid. This is because the milk and wool are not what is intended when a person purchases a sheep that has milk and wool in exchange for milk and wool. The proof that they are not intended is that he will value the sheep itself against the milk and wool he possesses, without giving any attention to the wool on its back or the milk in its udder. Since these are not intended, the matter does not fall under the case of “a mudd of ʿajwah dates and a dirham.”

From this, we learn that if something of the same kind accompanies a riba-bearing commodity but is not intended, it has no effect—such as spices and similar things used to season food. The preceding discussion was based on the view that milk and wool are subject to riba.

The correct view is that wool is not subject to riba. As for milk, if the people of a locality are accustomed to treating it as a staple food, then we class it with wheat, dates, and barley. But for those who do not regard it as a staple food, as is the case among us in Najd, then it is not