is as follows:
The default ruling for all transactions, forms of trade, and means of earning is permissibility. Nothing is barred except what Allah and His Messenger have forbidden.
This is a mighty principle upon which every financial dealing and customary practice relies. Whoever claims that a given transaction is unlawful must furnish evidence, for his claim departs from the default. Through this the broad-mindedness and expansiveness of the Sharia become clear, together with its fitness for every age and place and its ability to develop in line with human circumstances and interests.
It is a constant rule founded on justice, equity, and regard for the welfare of both parties. A transaction is not shifted from permissibility to prohibition unless it is accompanied by some objectionable element that involves wrongdoing to one of the two parties—such as riba (usury), gharar and jahālah (uncertainty and excessive risk), or khidāʿ and taghrīr (fraud and misrepresentation).
On reflection, each of these forms of dealing boils down to injustice toward one of the contractors. All prohibited transactions trace back to these parameters, and they have been forbidden only because of the corruption and oppression they entail. The wise and merciful Lawgiver has prescribed everything conducive to benefit and has warned against everything leading to harm.
In short, the unlawful transactions revolve around a set of criteria, the greatest of which are the following three:
- Riba in its three kinds: riba al-faḍl (excess in barter), riba al-nasīʾah (deferred usury), and the usury of loans.
- Jahālah and gharar (uncertainty and excessive risk), which encompass many detailed cases and varied forms.
- Khidāʿ and taghrīr (fraud and misrepresentation), which likewise take many shapes.
This is their outline; their specifics will appear—if Allah wills—in the hadiths to come.
Hadith One
From ʿAbd Allah ibn ʿUmar (may Allah be pleased with them both), from the Messenger of Allah ﷺ, who said:
“When two men enter into a sale, each of them retains the option (to cancel) so long as they have not separated and remain together, or until one of them grants the other the choice. If one grants that choice and they then conclude the sale on that basis, the sale becomes binding.”
Hadith Two
To the same effect is the report of Ḥakīm ibn Ḥizām, who said: The Messenger of Allah ﷺ said:
“The two parties to a sale have the option (to cancel) so long as they have not separated—or he said: until they separate. If they are truthful and make everything clear, their transaction will be blessed; but if they conceal and lie, the blessing of their sale will be wiped out.”