fuel/fuel/core/classes/validation.php
public function set_message($rule, $message)
	{
		if ($message !== null)
		{
			$this->error_messages[$rule] = $message;
		}
		else
		{
			unset($this->error_messages[$rule]);
		}

		return $this;
	}
public function set_message($rule, $message)
	{
		if ($message !== null)
		{
			$this->error_messages[$rule] = $message;
		}
		else
		{
			unset($this->error_messages[$rule]);
		}

		return $this;
	}
public function set_message ( $ rule , $ message ) { if ( $ message !== null ) { $ this -> error_messages [ $ rule ] = $ message ; } else { unset ( $ this -> error_messages [ $ rule ] ) ; } return $ this ; }
This will overwrite lang file messages for this validation instance

@param   string
@param   string
@return  Validation  this, to allow chaining
This will overwrite lang file messages for this validation instance