What is the explanation of the hadith: "Whoever intercedes for his brother with an intercession, and he gifts him a gift for it, and he accepts it, then he has approached a great door from the doors of usury"?

Intercession is mediating on behalf of another to bring a benefit or ward off harm. If the intercession is for a good cause, it is a righteous deed for which the doer is rewarded. It is forbidden to accept a gift for intercession because it is considered ill-gotten gain (suḥt) and resembles usury. The early Muslims (Salaf) stated that accepting a gift for intercession negates its reward, as it is money taken without an equivalent exchange.

It is not permissible to accept a gift for intercession that involves assisting in an obligatory act or refraining from a forbidden one. However, there is no harm in taking payment for effort and work expended by the intercessor. In summary, accepting a gift for obligatory or forbidden intercession is prohibited, and this prohibition is even stronger for rulers, judges, and managers. As for permissible intercession, scholars have differed on the permissibility of accepting payment for it.