Section: Items for which equality is not stipulated—such as two different genera, and what contains no usury—may be sold for one another by measure, by weight, or by estimation (juzaf). This is the apparent view in the words of al-Khiraqi, due to his specification that what is measured is prohibited from being sold for something of its own genus by weight, and what is weighed is prohibited from being sold for something of its own genus by measure. This is the opinion of the majority of scholars. Ibn al-Mundhir stated: The scholars have reached a consensus that the sale of a heap (subra) of food for a heap of food—when the measure of either is unknown and they are of the same kind—is not permissible, but there is no harm in it if they are of two different kinds, based on his [the Prophet's] statement, peace be upon him: "So if the two kinds differ, sell as you wish" (7). A group of our colleagues went to the extent of prohibiting the sale of a measured item for a measured item by estimation, and a weighed item for a weighed item by estimation. Ahmad said, in a report by Muhammad ibn al-Hakam: "I dislike that." Ibn Abi Musa said: "There is no good in selling what is measured for what is measured by estimation, nor in what is weighed for what is weighed by estimation, whether the genera are the same or different. However, there is no harm in selling a measured item for a weighed item by estimation." The Qadi and al-Sharif Abu Ja'far said the same, because the Prophet - may God bless him and grant him peace - prohibited the sale of food for food by estimation (8), and because it is a sale of a measured item for a measured item, thus it resembles the single genus.

As for us, we rely on the statement of the Prophet - may God bless him and grant him peace -: "If these kinds differ, then sell as you wish, hand to hand" (9). Furthermore, the word of God Almighty: "And God has permitted trade" (10) is general, which we have qualified in the case of a single genus in which equality is required; therefore, regarding all else, we must remain upon the generality [of the verse]. Additionally, because disparity is permissible therein, estimation from both parties is permissible, just as in the case of selling a measured item for a weighed item. This is further supported by the fact that if the reality of excess does not prevent the sale, then the mere probability of it is even more entitled to not being a prevention. His [the Prophet's] hadith was intended to refer to the single genus; this is why it appears in some of its versions: He prohibited the sale of a heap of dates whose measure is unknown for a heap of dates whose measure is unknown.