Islam has strictly forbidden this type of contract in order to block the means to disputes and all forms of injustice. In fact, it declares it prohibited even if it may be an acceptable practice amongst people, for the prophet ﷺ has forbidden sales which involve deception through ignorance. (Saheeh Muslim: 1513)
Examples of sales contracts that involve deception through ignorance
1
Selling fruits before they ripen and become ready for picking. Indeed, the prophet ﷺ has forbidden the sale of dates until their benefit becomes evident and suitable for eating, for there is a chance that they may become decayed and never ripen.
2
Paying a certain amount of money to purchase a box without knowing whether its contents are valuable or worthless.
Circumstances under which gharar (ignorance and uncertainty) may affect the contract
Ignorance and uncertainty (gharar) may only affect the contract and render it impermissible if the contract involves a great deal of it and if it relates to the object of the contract.
Therefore, a Muslim may purchase a house even if he is not aware of such things as the type of building materials used in the construction of the house and the type of paint used in painting it, for such ignorance is rather trivial and does not affect the object of the contract.
