Is it permissible to take money from donations for the treatment of a volunteer, and is it permissible to offset that against his efforts and donations to the charity?

Those in charge of charitable work are agents for the donors, and they must adhere to the donors' conditions. If there is no condition, they may act in a way that serves the beneficiaries' interests. If the agent is eligible for charity, he may take from it without the principal's knowledge, although it is better to refrain from doing so. The agent must guarantee any money placed improperly, return any surplus administrative funds to the association, and guarantee what he spent on himself. What the agent donated in terms of money or effort cannot be counted against his guarantees. The agent is not allowed to take a salary for his work unless authorized by the association's management. These rulings apply if the donations are for the agent personally or if the donors authorized him to dispose of them outside the association's account. However, if the donations are received by him in his capacity as an employee of the association to be deposited into its account, he is absolutely not allowed to dispose of them. The agent's liability is not discharged by him waiving an 'Umrah he earned from the association in exchange for a financial guarantee, because 'Umrah is an act intended for itself.