His statement, “or someone able to retrieve it,” means: able to retrieve it from the usurper. For example, if someone usurps it and the owner sells it to that person’s paternal uncle, who is able to retrieve it from him, or to his father, then the sale is valid, because the effective cause for the validity of the sale—namely, the ability to retrieve it—is present. If, however, the buyer purchased it on the basis that he was able to retrieve it, but later proved unable to do so, then he has the right to rescind the sale, because attainment of their intended purpose has become impossible.

His statement, “and that it be known through inspection or description”: this is the sixth of the conditions of sale—that the item being sold be known through inspection or description, by both the seller and the buyer. It is not sufficient for only one of them to know it. Ignorance may be shared by both of them, or may be on the part of the seller alone, or the buyer alone; in all three cases, the sale is invalid. Thus, it must be known to both contracting parties. The evidence for this is the hadith of Abu Hurayrah, may Allah be pleased with him, that the Prophet ﷺ forbade sales involving excessive uncertainty (1). There is no doubt that selling an unknown item involves excessive uncertainty.

If it is asked: Why were sales involving excessive uncertainty forbidden?

We say: because they give rise to hostility, rancour, and resentment; for the one who loses out will come to resent the one who gains. It is for this reason that sales involving excessive uncertainty were forbidden.

Issue: Is it a condition that the buyer have knowledge of the item being sold? For example, if the item being sold is a jewel—and it is known that those knowledgeable about jewels are a specialized class—and one wishes to sell this jewel to a person who cannot distinguish pottery from pearls, then the apparent meaning of the jurists’ statements is that this is permissible, even