function hook_form_validate($form, &$form_state) {
$errors = form_get_errors();
if ($errors) {
// Clear errors.
form_clear_error();
// Clear error messages.
$error_messages = drupal_get_messages('error');
// Initialize an array where removed error messages are stored.
$removed_messages = array();
// Remove all errors originated by the 'foo][bar' element.
foreach ($errors as $name => $error_message) {
if ($name == 'body][und][0][value') {
$removed_messages[] = $error_message;
unset($errors[$name]);
}
}
// Reinstate remaining errors.
foreach ($errors as $name => $error) {
form_set_error($name, $error);
// form_set_error() calls drupal_set_message(), so we have to filter out
// these from the error messages as well.
$removed_messages[] = $error;
}
// Reinstate remaining error messages (which, at this point, are messages that
// were originated outside of the validation process).
foreach (array_diff($error_messages['error'], $removed_messages) as $message) {
drupal_set_message($message, 'error');
}
}
}
Source: http://goo.gl/nI55mb