Conditions of Sale and Prohibited Transactions

The chapter on commercial transactions (mu'amalat) in al-Sharh al-Mumti' reflects the Hanbali school's comprehensive engagement with the economic sphere of Muslim life. Ibn Uthaymin begins by establishing that commerce is fundamentally permitted — the Quran explicitly permits trade and forbids usury (al-Baqarah 2:275) — but that the Sharia has placed certain conditions on valid transactions and forbidden categories of transactions that cause injustice, uncertainty, or involve prohibited substances.

The conditions for a valid sale are analyzed by Ibn Uthaymin under several categories. The conditions related to the contracting parties (al-'aqidan) are: both must have legal capacity (they must be sane and of the age of discernment), they must be acting voluntarily without coercion, and both must consent to the transaction. The Prophet said: "Sale is only by mutual consent." A sale conducted under duress — where one party is compelled to sell or buy under threat — is invalid.

The conditions related to the subject matter of the sale (al-mabi') are: the goods must exist at the time of the contract (one cannot sell what one does not yet possess), they must be of value in the Sharia (one cannot sell wine or pork or other prohibited items), they must be owned by the seller or the seller must have authority to sell them, they must be deliverable (one cannot validly sell a bird in the sky or fish in the sea that one has not caught), and the price and goods must be known to both parties to eliminate gharar (uncertainty).

Riba — usury or interest — is the most comprehensively prohibited category of transaction in Islamic law. Ibn Uthaymin explains the two main categories: riba al-fadl (exchanging the same type of ribawi goods in unequal quantities, such as one kilogram of gold for one and a half kilograms of gold) and riba al-nasiah (deferring the exchange of ribawi goods or any loan transaction that returns more than the principal). The six ribawi goods specified in the hadith — gold, silver, wheat, barley, dates, and salt — are subject to specific rules: they must be exchanged hand to hand (spot, not deferred) and in equal quantities when exchanged for the same type. Ibn Uthaymin extends the analysis to modern paper currency and bank interest, affirming that conventional bank interest is riba al-nasiah and strictly prohibited.

Gharar — uncertainty and deception — is the second major category of prohibited transactions. The Prophet forbade sales of gharar. This prohibition covers: selling goods before taking possession of them (which carries the risk that one cannot deliver), selling undefined quantities from a heap, and all forms of speculative transactions where the subject matter or price is unknown or contingent on future events in a way that could harm either party. Ibn Uthaymin carefully distinguishes between tolerable minor uncertainty (which is unavoidable in commerce and forgiven) and excessive uncertainty that exposes either party to unfair loss.

The chapter also covers prohibited sales such as: the sale of forbidden substances (wine, pork, idols), the urban resident acting as agent for the rural person without the latter's knowledge (bay' al-hadir lil-badi), artificial price-raising through false bidding (al-najash), and pre-emption rights (shuf'ah). Ibn Uthaymin presents these prohibitions with their evidences and the wisdom behind them, showing that Islamic commercial law is not arbitrary restriction but a comprehensive system for ensuring fairness in the marketplace.