Add new field to node form on validate I am performing a hook_node_validate() and would like to add a new field (e.g. a textfield) during the processing of this function.  Is this possible?  If so could someone let me know how to do it.  I am tried to following so far w/ no luck:

function hook_node_validate($node, $form, &amp;$form_state) {
    $form['content_type_node_form'] = array(
        '#title'    =&gt; t('Phone'),
        '#type'     =&gt; 'textfield',
        '#required' =&gt; TRUE,
    );      
    form_set_error('time', t('Stop submission to add new field'));
}


Thanks, 
Derek
I'm guessing what you actually want (from a user story perspective) is if a certain condition is met another, otherwise hidden, field is shown. As @geoff points out that field would need to exist on the content type.

I believe the correct way to do this within the Form API is with the #states parameter in order to conditionally show/hide the phone field. 
https://api.drupal.org/api/drupal/developer!topics!forms_api_reference.html/7#states