What is the ruling on brokerage in medicine in exchange for referring patients to other clinics, laboratories, or radiology centers?

It is forbidden for a physician to receive a commission for referring a patient to a pharmacy, laboratory, or private physician, because either it is during official working hours, and the physician receives a salary for his work, so it is not permissible for him to take a commission. Or, it is outside working hours, and the referral is unnecessary or when a better option exists for the patient, which constitutes deceit and betrayal. However, if it is outside working hours and without deceit, the commission is prohibited as a preventative measure, because it leads to the physician's eagerness for profit and referring patients to whoever pays a commission, even if it is not in the patient's best interest.