《资治通鉴·唐纪·唐纪二》
府掾柳燮说： 明公和唐公是同一宗族，又加上有过去联合的友谊；虽然没有随唐公一同起兵，但阻隔东都，切断了隋军的归路，使唐公不战而占领了长安，这也是您的功劳。 
府掾柳燮曰： 明公与唐公同族，兼有畴昔之好；虽不陪起兵，然阻东都，断隋归路，使唐公不战而据长安，此亦公之功也。 
The Prefect Liu Xie said: Your Honor and Duke Tang are from the same clan and have been united as friends in the past. Although you did not start an uprising with Duke Tang, you blocked Dongdu and cut off the Sui army's return route, allowing Duke Tang to occupy Chang'an without a fight. This is also your contribution.