《后汉书·列传·冯岑贾列传》
就回书冯异说： 我本来与光武首谋兴汉事宜，结生死之约，同成败之计。
乃报异书曰： 轶本与萧王首谋造汉，结死生之约，同荣枯之计。
He wrote a letter back to Feng Yi to say: I and Guangwu discussed the matter of restoring Han Dynasty and pledged a life and death pact, and agreed upon the plan of successes and failures.