The Rules of Buying and Selling

1. It is Wajib that a person learns the rules of buying and selling that he will commonly have a need for.
2. It is Haram to sell and rent a house or other things that will be used for Haram.
3. Buying and selling, keeping, writing, and reading newspapers, magazines and books that can lead people astray is Haram, and the same applies for teaching from such books. (A person can sell such things if) he knows that the person who will buy them is a person who is sound in his beliefs, and (who is buying them) for a good reason like to answer questions raised in these items.
4. It is Haram to sell a product which has been mixed with something else such that it is not clear what the product is, or if the seller of the product does not inform the purchaser. For example, milk that has been mixed with water. (Such an action is called Ghash).
5. In transactions, the exact product that is being bought and sold must be specified, but it is not necessary to mention the specifics – such that if stated or not would not have an effect on the desire or inclination of the people in relation to that product.
6. In the buying and selling of two things which are of the same type and which are sold by weight or quantity, if more is sold, it is called Riba (Interest) and is Haram; for example, one gives one tone of wheat, and in return, takes 1.2 tones.
7. It is Mustahab that the person selling does not differentiate in the price between the people buying from him. In addition, one should not be firm in one’s price, and if the buyer or seller wishes to cancel the transaction, then the other person should agree to it.
8. It is Haram to take an oath during transactions if that which is said is a lie, and if what is said is true, then it is Makrooh.