• Nor is there any distinction with trade carried out through export and import from one region to another.
• Nor is there any distinction whether buying-and-selling and profit-making are pursued individually or in partnership.

All these forms of commerce and everything connected to them have been permitted and left unrestricted by the Lawgiver, as a mercy to His servants, to secure their interests, and to ward off harm.

They are all lawful together with any conditions, contracts, documentation, and the like that usually accompany them, provided they are free of the sharʿī impediments to which Allah and His Messenger have drawn attention. This blanket permission embraces every category, type, and individual item that can be sold: real estate, animals, merchandise, foodstuffs, vessels, beverages, clothing, furnishings, and so forth.

Each of these transactions, however, must be accompanied by the condition Allah has stipulated—mutual consent between the two contracting parties, consent that is informed and deliberate. As for the prodigal, the insane, or anyone whose speech carries no legal weight, his guardian conducts transactions on his behalf.

• The gravest factors that invalidate transactions are ribā (usury), gharar (excessive uncertainty), and injustice.

• Ribā, which Allah and His Messenger have prohibited, includes:
• Ribā al-faḍl: exchanging a commodity sold by measure for the same commodity, also sold by measure, with disparity; or exchanging a commodity sold by weight for the same commodity, also sold by weight, with disparity.

For this category to be lawful, the Lawgiver has stipulated (1) that the two items exchanged must be equivalent according to their sharʿī standard of measure, whether by volume or by weight.