You should let others jealous when it is at the expense of your good because god has not only sent him on the planet to live life. we all have the right to live a good life. At the most you can help him do that but if he is jealous even doing well because of the fear of others getting ahead of him then you shouldn’t care for the person because that person is not the only one who has taken birth to live life. He is simply egoistic.