《旧五代史·后周·列传六》
第二年，契丹人派使者给晋高祖加称颂功德的徽号，晋高祖也给契丹国主献上徽号，对冯道说： 此行非您去不可。 
二年，契丹遣使加徽号于晋祖，晋祖亦献徽号于契丹，谓道曰： 此行非卿不可。 
The following year, the Khitan people sent ambassadors to praise Emperor Gaozu of Jin. Emperor Gaozu of Jin also gave a title to the Khitan monarch, and said to Feng Dao, “You must go on this trip.” 