All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
If referring patients or sending people who want to get a visa to a particular clinic or hospital is for reasonable reasons, like the competence of the doctor who works there, or for the quality of the testing equipments there, then it is permissible to take a commission for this. However, if this is just a matter of favouritism, then it is not permissible to take this commission.
For more benefit, please refer to Fatwa 83648.