What is the ruling on a physician working as a medicine salesperson in a pharmacy, and is he liable for the harm that befalls a patient due to the medication? And what is meant by liability?

There is no harm in guiding a patient to the appropriate medication if the following conditions are met: knowledge of the medicine and its suitability for the patient, that it be in simple, common matters that do not require examination or analysis, and that it not be for the purpose of promoting a specific medicine when a more beneficial one exists. This act is considered an act of benevolence and alleviation for people. As for a physician's liability, the basis for it is the hadith: "Whoever practices medicine without being known to be skilled in it is liable."