Do walls or Wolves have ears?

[mimififi30]

My sister and I were talking the other night about her husband's birthday present. She lowered her voice, put her finger to her lips and said "Ssh, wolves have ears". I burst out laughing and explained that the phrase was 'walls have ears', but, as they say, she was having none of it. Afterward I was thinking that she is my older sister and maybe it is me that is wrong...does any one know the answer to this, and where does it originate from?? Many thanks.