$re = '/(?<=required)\s:\s+\'(.+)\',|(?<=dateISO)\s:\s+\'(.+)\'/';
$str = '{ messages : { required : \'This \'asdf\' "asdf" field is required!\', dateISO : \'This is a test...\' } , rules : { dateISO : true , required : true } }';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php