Is it permissible for an official in charge of collecting donations for mosque renovation to purchase renovation supplies in installments at a higher price, then sell them to the mosque at their cash price, on the condition that he bears the price difference from his own money, with the intention of benefiting from the money without harming the mosque's renovation?

Donations must be spent solely on the mosque’s renovation. The agent is not permitted to use them for any other purpose. If the Imam purchased mosque supplies with his own money, he is not allowed to sell them to the mosque while he is its agent, as this is considered an agent buying from himself for his principal, which is impermissible according to the majority of scholars unless explicitly authorized by the principal.

Scholars have differed on the ruling of an agent purchasing from his own property for his principal: Hanafis: This is impermissible even if the principal gives permission, because the rights revert to the agent, which results in one person being both seller and buyer simultaneously, and he is accused of buying from himself. Malikis (the relied-upon opinion) and Hanbalis: An agent cannot purchase from his own property for his principal because the common practice is to buy from others, and because it entails an accusation against him. An exception is made if the principal explicitly authorizes the agent, in which case it is permissible due to the absence of suspicion. A saying among Malikis: An agent may buy from himself if he does not favor himself. From Ahmad: It is permissible, just as if he were authorized or had someone else buy it. Shafi’is: An agent may not purchase from his own property for his principal under any circumstances, even if authorized, because the fundamental principle is that the offeror and acceptor should not be the same entity, and because if he were authorized to donate from himself, it would not be valid.

The disagreement applies when the principal has not given permission. If he permits him to buy from himself, it is permissible. This ruling also applies to an agent buying for himself, to a ruler and his trustee, to a guardian and a supervisor of an endowment, and to a mudarib (partner in profit-sharing).