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Conditions Stipulated for the Commodity and Its Payment
2118. The commodity that is sold and the payment acquired in return must possess the following five conditions:
1. Its measure must be known either by weight, volume, count or any similar method of measurement.
2. The item should be deliverable. If the seller—for example—sells an item that he is unable to deliver, but the buyer is able to acquire it, it will suffice. Therefore, if--for example—someone sells a horse that has run away, and neither of the parties is able to capture it, the transaction will be void.
However, if he sells a runaway horse along with something of value that is deliverable, the transaction will be valid even if the horse is not located. The more precautious measure—in the case of things other than runaway slaves—is that the seller should sell a commodity of value, and stipulate within the transaction that should the runaway be located, it will be the property of the buyer.
3. The details of the commodity and the item acquired in return, which are responsible for the difference in its price, should be specified.
4. The ownership of the commodity should be unconditional. Hence, the sale of a property that has been dedicated (waqf) is not permissible, except in the cases which will be mentioned later.
5. The commodity itself should be sold and not its benefits. Hence, if someone, for example, sells one year’s worth of benefits acquired from a house, it will not be valid. However, there is no problem if the buyer offers the benefits to his property instead of money, such as the case wherein he buys a carpet from an individual and in return he gives him a year’s worth of benefits to his house.
The rulings pertaining to these conditions will be elaborated in subsequent articles.

2119. Precaution dictates that a commodity that is sold by weight or volume in a particular city, be bought by weight or volume in that city. However, he may buy the same commodity by mere observation in another city where it is sold by observation.

2120. A commodity that is transacted by weight, may also be transacted by volume, wherein—for example—a person who wishes to sell 10 kgs of wheat, may use a measuring cup that has the capacity for 1 kg of wheat, and measure 10 such cups.

2121. If even one of the conditions that were mentioned earlier is not present in a transaction, it will be void. However, if both owners consent to the use of their property by each other, then there is no objection to their use of each other’s property in ways which are not contingent on ownership.

2122. The transaction of a thing which has been endowed is not valid. However, if it has been damaged to an extent that it is no longer usable for the purpose that it was endowed for, or is close to reaching such a stage, such as the carpet of a mosque, that is damaged to an extent that one cannot pray on it, then there is no problem in selling it. Wherever possible, its replacement should be put to use in the same mosque in a manner that is most congruous to the aims of the endower.
The endowed property should be sold by its trustee, and any use of the property acquired in return should also be carried out by him. In the event that he is not available, it should be carried out with the permission of the ¦¡kim al-shari’yy.

2123. Whenever a dispute arises between the beneficiaries of an endowment, to a degree that if the endowment is not sold, one would fear for the loss of the endowment or the loss of a life, then it may be sold. In such a case, in return for what is sold, a thing should be bought, and in accordance with the former endowment, the profits acquired from it should be spent on the affairs specified by the endower. In the event that this is not possible, it should be spent on affairs which are most congruous to the aims of the endower.
The same will apply if the endower stipulates that if the general interest is upheld by selling it, that it be sold.

2124. There is no problem in selling or purchasing a property that has been rented out. However, the benefits of the property belong to the renter for the length of the rental period.
In this case, if the buyer was not aware that the property has been rented out, or under the impression that the rental period is short, before he chooses to buy it, he can cancel the transaction upon finding out.