Nor is it permissible to sell a Muslim slave to a non-Muslim when doing so would place him under the latter’s authority, for that entails humiliation and abasement of a Muslim before a disbeliever. Allah the Exalted says, “And Allah will never grant the disbelievers any authority over the believers” (Q 4:141). The Prophet ﷺ likewise said, “Islam is uppermost, and nothing is above it.”

It is also forbidden to sell against the sale of your fellow Muslim—for example, saying to someone who has just bought a commodity for ten, “I will give you the same for nine,” or, “I will give you a better one for the same price.” The Prophet ﷺ said, “None of you may sell against the sale of another,” and, “A man must not sell against his brother’s sale”—both reports are agreed upon.

The same prohibition applies to buying against another’s purchase, as when one says to a seller who has concluded a sale for nine, “I will buy it from you for ten.”

Such unlawful dealings are all too common today in Muslim marketplaces. A Muslim is therefore obliged to avoid them, to forbid them, and to denounce anyone who practices them.

Among the forbidden transactions is the sale in which a resident acts as an agent for a Bedouin. The resident is