for some of it except on a like-for-like basis, hand to hand, even when the kinds of grain from which the breads are made differ. Some scholars of Medina, however, treat each variety of bread according to the ruling of its original grain.

All vinegar, according to Mālik, belongs to a single genus—whether it is grape vinegar, date vinegar, or honey vinegar—and it may not be exchanged one for another unless the transaction is hand to hand and equal in measure; the disagreement about vinegar is exactly the same as the disagreement about bread.

Oils, by contrast, are separate genera: all olive oil forms one genus; radish-seed oil another; linseed (flaxseed) oil another; and sesame oil yet another. It is permissible to trade one of these kinds of oil for another with disparity, provided the delivery is immediate; but within any single genus none of it may be bartered for its own kind except equal for equal, hand to hand.

All olives, as fruit, make up a single genus, and sesame likewise constitutes one genus.

In the view of Mālik and his companions, all milk is a single genus: the milk—whether fresh, curdled, or buttermilk—of any four-footed animal whose meat is lawful to eat. None of it may be sold for its own kind except equal for equal, hand to hand.

The same rule applies to the meat of grazing livestock, both wild and domesticated—camels, cattle, sheep, rams, wild asses, and every other four-footed animal whose flesh is permissible. Their meat is one genus, and the meat of any of them may not be exchanged for the meat of another except equal for equal, hand to hand. Nor may such meat be traded for a live animal of its kind—even one already slaughtered and skinned—for the Prophet forbade selling a living creature for meat.

Mālik does permit the exchange of meat for meat on the basis of careful estimation when the quantity involved is small enough to be fully known, but not when it is large and cannot be precisely accounted for.

All bird meat likewise forms a single genus. Every feathered creature—whether land birds, waterfowl, birds of prey, or any other variety—is included, and the meat of any of them may not be traded for the meat of another except equal for equal or on the basis of exact estimation.