The commodity which is sold, and the thing which is received in exchange, should fulfill these conditions:
- Its quantity should be known by means of weight or measure or counting etc.
- It should be transferable, otherwise the deal will be void, except when a transferable object is supplemented to it. But if the buyer can himself manage to find the thing he has bought, even if the seller is unable to hand it over, the deal will be valid. For example, if a person sells a horse which has run away, and the buyer can find it, the transaction will be valid, and there will be no need to supplement it with any transferable object.
Those details of the commodity, and the thing accepted in exchange, which influence the minds of the people in deciding about the transaction, must be clearly described.
- The ownership should be unconditional, in a manner that, once it is out of his ownership, he forsakes all his rights over it.
- The seller should sell the commodity itself and not its profit. Hence, if he sells one year’s profit of a house, it will not be in order. But, if a buyer gives profit of his property in exchange, like, if he buys a carpet from someone and in lieu thereof gives him the profit of his house for one year, there is no harm in it. Details of these will come later.
- If a commodity is sold in a city by weight or measurement, one should purchase that commodity in that city by weight or measure. But if the same commodity is sold in another city at sight, one can purchase it in that city at sight.
- A commodity which is normally sold by weighing, can also be sold by measure. For example, if a person wants to sell ten kilos of wheat, he should fill a measure which takes one kilo of wheat, and give ten such measures to the buyer.
- If the transaction has become void because of the absence of any of the aforesaid conditions, except the fourth – but the buyer and the seller agree to have the right of discretion over their exchanged commodities, there is no objection if they do so.
- The transaction of a Waqf property is void. However, if it is so much impaired, or is on the verge of being impaired, that it cannot be possibly used for the purpose for which it was dedicated, like, if the mat of a mosque is so torn, that it is not possible to offer prayers on it, it can be sold by the trustee or someone in his position. And if possible, as a precaution, its sale proceeds should be spent in the same mosque, for a purpose akin to the aim of the person who originally waqfed it.
- When serious differences arise between the persons for whom waqf is made, to the extent that it may be feared that if the waqfed property is not sold, property or life of some person is endangered, some Fuqaha have ruled that the property may be sold off, and the sale proceeds be spent for a purpose akin to the object of the person who originally made the waqf. But this rule is not devoid of Ishkal. But if the person who made waqf made a condition that it be sold when advisable, then there will be no objection to it being sold off.
- There is no harm in buying and selling a property which has been leased out to another person. However, the leaseholder will be entitled to utilize the property during the period of lease. And if the buyer does not know that the property has been leased out, or if he purchases it under the impression that the period of lease is short, he can cancel the transaction when he comes to know of the true situation.