preach to deaf ears

(idiomatic) To attempt to persuade a party that does not wish to listen or cannot be altered in its conviction.

Example: 2002, Edward M. Bennet, Separated by a Common Language: Franklin Delano Roosevelt and the Anglo-American Relations, 1933-1939, Writers Club Press, ISBN 9780595222926, page 126:
  Roosevelt was tired of preaching to deaf ears. He was ready to try something else.