Is the sum of money received by the surgeon lawful, given the knowledge of other doctors and the patients' lack of knowledge of the surgeon's identity after anesthesia?

It is permissible for a joint employee, whose benefit is measured by work, to hire someone else to perform his work, unless the hirer stipulated that he must perform the work himself, or if he hired him for a specific quality he possesses, such as proficiency. If there is a particular characteristic that varies among individuals, it is not permissible to substitute someone else, such as copying books with a specific handwriting. If a patient intended to see a specific doctor due to his trust in him, the doctor is not allowed to substitute someone else in his place, and he must guide the patient to a more competent person if he is not qualified. If that is not feasible, he must explain to the patient the possibility of someone else performing the work. If the doctor is permitted to substitute someone else, then accepting this work is permissible. If the doctor does not do so, and the substitute doctor is more skilled and beneficial to the patient, there is no harm in accepting the surgery, even if it is under the supervision of the original doctor or in his name, for the sin then falls upon the original doctor for his lack of trustworthiness.