The answer is that this case may be understood in either of two ways. It may be said that it is sufficiently known, and that the buyer’s ignorance of how to use it does not amount to ignorance of the item being sold itself; rather, it is a deficiency in the contracting buyer, not in the subject matter of the contract.
Or it may be said that this too must be known. An inexperienced person may come along, see these machines operating and moving before him, and imagine that they produce bombs or airplanes, so he buys one at an exorbitant price—only to find that it cannot produce even a needle. This would be grave ignorance. Therefore, we hold that a person must know how this thing may be used; otherwise, there would be excessive uncertainty.
His statement, “Or if it is described to him in a manner insufficient for a salam sale, it is invalid”: this is because the item being sold is not known. The subject of salam—Allah willing—will come later: what can be precisely defined and what cannot. Thus, if it is described in a manner insufficient for a salam sale, the sale is invalid.
It was also said that it is valid to sell something which the buyer has not seen and which has not been described to him, while the buyer retains the option to proceed or withdraw once he sees it. For example, he says, “I have sold you my car.” The other asks, “What kind of car is it?” He replies, “Allah willing, you will see it and know it.” He asks, “For how much?” He replies, “For five thousand.” The other says, “I have bought it.”
According to the madhhab, the sale is invalid, because he has neither seen it nor had it described to him.
Abu Hanifah’s—may Allah have mercy on him—view is that the sale is valid, and that the buyer has the option when he sees it. This is the correct view, and it resembles a sale conducted by an unauthorized agent, because if the buyer has the option upon seeing it, he suffers no disadvantage.
If it is asked: How can the sale be validated according to the first view?
The answer is that, once he sees it, they enter into a new contract. This is where the practical consequence of the disagreement between the two views becomes apparent: according to the view that it is valid: