Is selling medical devices to doctors after purchasing them from importers at a commercial price lower than their selling price to the doctor forbidden?

If you sell an item after acquiring ownership through purchase, and what precedes that is merely a promise, then this is permissible and presents no problem. The mutual promise issued by both parties is permissible in a Murabaha sale provided there is an option [to cancel], otherwise, it is not permissible because it resembles the sale itself. In that case, it is stipulated that the seller must own the item being sold, so as not to violate the Prophet's (peace and blessings of Allah be upon him) prohibition against a person selling what he does not possess.