Thus, if a group buying or selling a particular kind of goods colludes to depress the value of what they buy, purchasing it below its recognized fair market price, while raising the price of what they sell above the customary price, and increasing what they purchase, this is a greater transgression than intercepting goods before they reach the market, a townsman selling on behalf of a desert dweller, or bidding up prices without intending to buy. They have thereby agreed to wrong people, forcing them to sell their goods and purchase them at more than their fair market value, even though people need these goods and need to purchase them. Whatever the public needs to buy and sell must be sold only at its fair market price, when the need to buy and sell it is general.
This includes people’s need for the work of particular trades, such as farming, weaving, and building. People must have food to eat, clothes to wear, and homes to live in. If sufficient clothing is not brought into their town—as it used to be brought into the Hijaz during the time of the Messenger of Allah (peace and blessings be upon him)—they need people to weave clothing for them. Clothing was brought to the Hijaz from Yemen, Egypt, and Syria, whose inhabitants were unbelievers; the Muslims wore what unbelievers had woven without washing it.
They must also have food, either brought in from elsewhere or grown in their own land, which is generally the case. Likewise, they must have homes to live in and therefore need builders. For this reason, a number of jurists among the followers of al-Shāfiʿī and Ahmad ibn Hanbal, as well as others, stated: