A type of ba’i al-gharar in which the object of sale or the price (thaman) is unknown/ unspecified, or in the case of a deferred price, the settlement date is unknown. As such, the sale becomes invalid (batil) because of uncertainty as to the price, object of sale, or settlement date. Most often, uncertainty results in disputes (munaza’ah) between the contracting parties (and hence comes the shari’a basis for impermissibility). An example is the sale of an unidentified good (e.g., piece of cloth) out of two or more. However, ba’i al-majhul is usually valid for settlement dates linked to some identifiable events such as harvest times, hajj, etc. This sale may also be permissible if it is embedded with an option of choice (khiyar al-ta’yeen) (in which case the transaction is called ba’i al-ikhtiyar), provided that the objects of sale are identical in terms of genus, kind, category, and price (otherwise, the sale is impermissible).

Based on ijma’a (consensus of fuqaha), gharar yaseer (a little deal of uncertainty) in commutative contracts (uqud al-mua’wadhah) can be ignored, i.e., it doesn’t render a contract impermissible or invalid (e.g., a buyer unknowledgeable of the state of a building’s foundations as such contractual aspects are not always known for certain). Different mazhahib (schools of thought) agree that ba’i al-majhul which involves an excessive degree of gharar (gharar fahish) is forbidden by shari’a.