Mvc\Model::appendMessage

use Phalcon\Mvc\Model;
 use Phalcon\Mvc\Model\Message as Message;

 class Robots extends Model
 {

   public function beforeSave()
   {
 if ($this->name == 'Peter') {
    $message = new Message("Sorry, but a robot cannot be named Peter");
    $this->appendMessage($message);
 }
   }
 }