jQuery variable selector Syntax error, unrecognized expression

I want to prepend html code into the DOM after receiving a nodejs message...

socket.on('new-message', function(message) {
    $(message).prependTo('#messages').hide().slideDown();
});

I get this error message:

Uncaught Error: Syntax error, unrecognized expression:

<li class="timeline-message">
    <div class="well">
        <div class="timeline-header">
            <img src="http://www.gravatar.com/avatar/8eb1b522f60d11fa897de1dc6351b7e8?s=50&amp;d=wavatar" alt="John" class="shadow" />
            <h4>
                New message from John<br/>
            </h4>
            <small>March 20th at 12:19am</small>
        </div>
        oo
    </div>
</li>

If I enclose the variable into tags it works well:

$('<div>' + message + '</div>').prependTo('#messages').hide().slideDown();

Thank you for your help.