for one kilogram of cooked meat is not permissible, because cooking affects the weight, as substances such as water enter into it. If the exchange is between different genera, however, it is permissible.

His statement, “nor its original substance for its extracted juice,” means that the original substance may not be sold for its juice. For example, if someone has olives and olive oil—the oil being extracted from the olives—and sells a pound of olives, whether more or less, for a pound of oil, the sale is invalid. Similarly, it is not permissible to sell dates for date syrup—the syrup being the liquid that comes out of dates—because equality cannot be established.

His statement, “nor its pure form for its adulterated form,” means that the pure form is that which has not been mixed with anything else, while the adulterated form is that which has been mixed with something else. Such an exchange is not permissible, because equality cannot be established.

For example, one man has a sāʿ of pure wheat, while another has a sāʿ of wheat mixed with barley. It is not permissible to exchange one for the other, because equality cannot be established. An exception is made, however, for a negligible admixture, or for something added to improve the mixture, such as salt in food. A slight admixture does not matter, since one can hardly find pure wheat containing no grain of barley. The same applies to something added for improvement: for example, if we sell wheat bread for wheat bread, and one of them has had sweetener added to it, but we sell them in equal amounts, there is no harm. Likewise, if one of them contains salt, there is no harm. Thus, a negligible addition, and something mixed in for improvement, are excepted from his statement, “nor its pure form for its adulterated form.”

His statement, “nor its fresh form for its dried form”: the pronoun in “its fresh form” refers to a ribawī commodity. That is, the fresh form of a ribawī commodity may not be sold for its dried form, such as selling fresh dates for dried dates. Dried dates are dry, while fresh dates are fresh, so this is not permissible, even if they are equal in weight;