Next and previous post with post thumbnails

single.php

     <?php $prevPost = get_previous_post();
                    $prevthumbnail = get_the_post_thumbnail($prevPost->ID,array(80,97)); ?>
                    <h2><?php previous_post_link('%link', 'Previous'); ?></h2>
                    <?php previous_post_link('%link', $prevthumbnail); ?>


            <?php // Display the thumbnail of the next post ?>

                        <?php $nextPost = get_next_post();
                    $nextthumbnail = get_the_post_thumbnail($nextPost->ID,array(80,97)); ?>
                    <h2><?php next_post_link('%link', 'Next'); ?></h2>
                    <?php next_post_link('%link', $nextthumbnail); ?>