code: public function getRedirectUrlForAuth()
      {
          //Oauth1 plugin to get access tokens!
          $oauth = new Oauth1(array(
              'consumer_key'    => $this->credentials->getConsumerKey(),
              'consumer_secret' => $this->credentials->getConsumerSecret(),
              'callback'        => $this->credentials->getCallbackUrl()
          ));
  
          $this->guzzleClient->getEmitter()->attach($oauth);
  
          //obtain request token for the authorization popup.
          $requestTokenResponse = $this->guzzleClient->post(
              Config::get('oauth_request_token'),
              array(
                  'auth' => 'oauth'
              )
          );
  
          //Parse the response from Twitter
          $oauthToken = array();
          parse_str($requestTokenResponse->getBody(), $oauthToken);
  
          //build the query parameters
          $params = http_build_query(array(
              'oauth_token' => $oauthToken['oauth_token']
          ));
  
          //return the redirect URL the user should be redirected to.
          return (Config::get('base_url') . Config::get('oauth_authenticate') . '?' . $params);
      }
docs: Get a request token and configures a Twitter authorization URL that the
  user will be redirected to for authentication.
  
  Then returns the prepared Twitter authorization URL.
  
  @return string authentication URL