Ruling 2100. The commodity that is sold and the thing that is taken as payment in exchange for it must fulfil the following five conditions [for the transaction to be valid]:

1. the amount must be known, either by weight, measure, number, or another similar method;

2. the person must be able to hand over the item; otherwise, the transaction is not valid unless he sells the thing with something else that he can hand over, in which case the transaction is valid. However, if the buyer can acquire the thing that he has bought even though the seller is unable to hand it over to him, the transaction is valid. For example, if someone sells a horse that has run away and the buyer is able to find it, there is no problem with the transaction; it is valid and there is no need to include something that he can deliver;

3. the particulars of the commodity and the payment in exchange must be known. ‘Particulars’ here are those things that affect one’s decision concerning the transaction [as opposed to inconsequential things];

4. there must not be any other right attached to the commodity or the payment in exchange in that once it ceases to be owned by the owner, he no longer has any right over it;

5. the commodity itself must be sold, not its usufruct. Therefore, if, for example, someone sells the usufruct of a house, the transaction is not valid. However, in the event that the buyer offers the usufruct of his own property instead of money, there is no problem; for example, he buys a rug from someone and in exchange he gives him the usufruct of his house for a year.

The rulings about these conditions will be explained below.

Ruling 2101. A commodity that is sold by weight or measure in a particular city must be purchased by weight or measure in that city. However, he can purchase the same commodity by viewing it in another city where it is sold by viewing it.

Ruling 2102. Something that is bought and sold by weight can also be transacted by measure; for example, a person wishes to sell 10 kilograms of wheat and uses a measuring vessel that has the capacity to hold 1 kilogram of wheat and sells ten of these measures.

Ruling 2103. If a transaction is void due to one of the conditions that were mentioned earlier – apart from the fourth condition – not being fulfilled, but the buyer and seller consent for the other to have disposal over their property, there is no problem in them having this disposal.

Ruling 2104. The transaction of something that has been given as a charitable endowment (waqf) is invalid. However, if the thing is damaged to the extent that it can no longer be used for the purpose for which it was endowed, or it is close to reaching this stage – for example, the ḥaṣīr[1] of a mosque is so torn that one cannot perform prayers on it – then there is no problem if the trustee (mutawallī) or someone who is ruled to be in his position sells it. But wherever possible, the money acquired should – based on recommended precaution – be used in the same mosque in a manner that is most congruous with the aims of the endower (wāqif).

Ruling 2105. If a dispute arises between the beneficiaries of a charitable endowment to the extent that it is supposed that not selling the endowment may result in the loss of property or the loss of life, then selling the endowment is problematic [i.e. based on obligatory precaution, it must not be sold]. However, if the endower makes a condition that it must be sold if it is advisable, then there is no problem in selling it in this case.

Ruling 2106. There is no problem in buying or selling a property that has been rented to someone else. However, the use of the property during the rental period belongs to the tenant/hiree (mustaʾjir). If the buyer does not know that the property has been given on rent or he bought the property supposing that the rental period is short, he can annul his transaction after discovering the situation.