“Anyone who is proud, it is as though he commits idol-worship.” Pride means that a person does not feel his lowliness, meaning that it is of great importance to a person that he is serving the Creator and not himself, since man is a lowly creature that is not worth caring for, and to spend all the years of his life with the sole purpose of serving and delighting himself, which is called “to serve man.”
However, he cannot serve his Creator, meaning feel the benefit in serving and delighting the Creator, and spend all his energy and thought on this, since he does not feel himself as lowly.
Rather, a person feels that it is more important to serve himself than to serve the Creator. This is regarded as a person being proud, and this is called “doing foreign work” [idol-worshipping], since he cannot serve the Creator, but rather serve himself, meaning work that is foreign to us.