for like, or with a disparity, so long as delivery is hand-to-hand. If deferment is introduced, the sale remains lawful within a single genus provided the quantities are equivalent, and both deferment and disparity are permissible when the two genera differ, just as with all other merchandise. Do you not see that, according to Mālik, it is impermissible to sell one garment for two garments of the same kind on deferred terms, or for a similar garment on deferred terms with an addition? All scholars agree that this constitutes usury and is prohibited.
Among foodstuffs there are cases in which it is not permissible to exchange one item for its like within the same genus—namely, when one portion is moist and the other dry. Although they belong to a single genus, equivalence is impossible both at the moment of exchange and afterwards, because the condition of the moist portion is unstable; once it changes, equivalence disappears and the forbidden disparity arises. It is related that the Messenger of Allah—peace and blessings be upon him—“forbade bartering rutab (fresh dates) for tamr (dried dates),” for the fresh dates shrink when they dry.
With regard to the genera (ajnās) as classified by Mālik—what his associates call the aṣnāf—wheat, barley, and sult (a type of barley) constitute a single genus in his view, since their value as staple food and their suitability for storage are nearly identical. The other jurists, however, treat them as three separate genera. Millet is a genus of its own, as are rice, sorghum, and ʿalas—also called al-ishqāliyya. Some of Mālik’s followers have counted ʿalas as a variety of wheat, but I do not accept that opinion.
All wheat, by unanimous agreement, forms one genus, even though its colors, some properties, and its particular names differ—riyūz, thumrah, samrāʾ, ḥamūlah, and the like. The same applies to all barley, to all dates despite their diverse colors and special names, and to all raisins, whether red or black: each of these is one genus.
Legumes (quṭānī), on the other hand, are distinct genera: fava beans are not the same as chickpeas, and lupines differ from lentils and cowpeas. It has been reported from Mālik that chickpeas—and likewise lupines—are distinct from lentils and cowpeas, and another report from Mālik