according to what it implies regarding validity and invalidity. For this reason, if one sells for a price and leaves it unqualified, and there are [various] currencies in the land, the contract is void; it is not construed as the currency of the city nearest to it. However, if he buys something from a person, it is valid, for the outward appearance is that it is his property, because possession is evidence of ownership. And if he sells meat, the outward appearance is that it is slaughtered [in accordance with Islamic law], because a Muslim, in outward appearance, does not sell carrion.

Section: As for if he sells two types of different value of a single genus, for one type of that same genus, such as a Moroccan dinar and a Saburi dinar for two Moroccan dinars, or a sound dinar and a clipped (quradah) dinar for two sound dinars, or for two clipped dinars, or red and dark wheat for white [wheat], or Barni and Ma'qili dates for Ibrahimi [dates], it is valid. Abu Bakr said: Ahmad alluded to this. Judge Abu Ya'la chose [the view] that the ruling regarding them is the same as the one preceding it. This is the school of Malik and al-Shafi'i, because the contract necessitates that the price be distributed over its compensation according to its difference in value, as we have mentioned. It was narrated from Ahmad that he prohibited this in currency and permitted it in price. Ahmad ibn al-Qasim transmitted this, because types of non-monetary items are frequently mixed, and it is difficult to distinguish them, so it is pardoned, unlike currencies. Our evidence is the statement of the Prophet (peace and blessings of Allah be upon him): "Gold for gold, like for like, and silver for silver, like for like" (the hadith). This indicates the permissibility of the sale when the observed equality exists, which is equality in weight for items that are weighed, and in volume for items that are measured. Furthermore, quality is irrelevant in the realm of usurious items regarding what is exchanged for its own genus, if the type is identical in each of the two sides; likewise if they differ. The difference in value is based on quality and inferiority, for he has sold gold for gold, equal in weight, so it is valid, just as if the type were the same. The compensation is only distributed over the item being compensated for in cases that include two genera, or in non-usurious items, as evidenced by one who sells a type for a type that includes good and inferior [items].