without measuring by volume or weight, or estimating the quantity, is impermissible, because this entails uncertainty and risk. If it is storable food, it also entails a failure to establish equality of quantity.
Partition by estimation is impermissible for goods measured by volume but permissible for goods measured by weight. Its permissibility is subject to the same disagreement as the permissibility of selling such goods by estimation.
Section
If, however, the goods do not form a single heap, one possibility is that they are commodities for which unequal exchanges are permissible, such as mahmūla and samrā’ wheat, wheat and barley, or clean grain and maghlūt grain. They may only be divided into equal quantities, using balance weights of known weight for goods sold by weight. For if two co-owners divide wheat and barley using a measure of unknown capacity, with one taking the wheat and the other the barley, the following problem arises—even if they take equal volumes and divide equally between them any surplus of wheat over barley, or barley over wheat, should either exceed the other: with respect to the wheat and barley that are equal in volume, each has exchanged his half with the other using a measure of unknown capacity. Exchanging wheat for barley using a measure of unknown capacity is impermissible, just as selling either using such a measure is impermissible. This entails uncertainty, since neither knows how much the unknown measure represents in known measures. The person taking the barley might say, “Had I known that it amounted to this many measures, I would not have agreed to take the barley and give him the wheat.” Had they divided the wheat separately and the barley separately, using a measure of unknown capacity would have been permissible, as explained above concerning a single heap.
If, on the other hand, the goods are commodities for which unequal exchanges are permissible, such as non-storable foods, henna, safflower, and the like, they may be divided either into equal or manifestly unequal portions, using a measure of known capacity or balance weights of known weight. They may not be divided using a measure of unknown capacity