the_post_thumbnail() for displaying page feautred image?

To display featured image of a specific page/post in anywhere:

    $the_id = 4; // The Page or post ID   
    echo wp_get_attachment_url( get_post_thumbnail_id($the_id, 'thumbnail') );

hope it will work, if not work try this:

$args = array('page_id => 4');
$featured_image = get_posts($args);
foreach($featured_image as $image) : setup_postdata($image);
   echo the_post_thumbnail();
endforeach;
wp_reset_postdata();