SO jQuery Fiddle
Test Fiddle mainly for SO Questions jQuery 1.4.3, UI 1.8.5
by Nick Craver
HTML
<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.5/themes/ui-lightness/jquery-ui.css">
<script src="http://ajax.microsoft.com/ajax/jquery.validate/1.7/jquery.validate.js"></script>
<form>
<textarea id="article_text"></textarea>
<button type="submit">Test</button>
</form>
JavaScript
$.validator.addMethod("regex", function(value, element, regexp) {
return this.optional(element) || regexp.test(value);
}, "Please include your keyword(s).");
$("form").validate({ debug: true });
$("#article_text").rules("add", { regex: /test phrase/i });