《汉书·纪·成帝纪》
公卿应认真思考朕的过失，明白地为朕指出。《尚书》说过： 你不要当面顺从唯唯，背后却有诽谤之言。 
公卿其各思朕过失，明白陈之。 女无面从，退有后言。 
The ministers and public officials should ponder my faults earnestly and point them out to me directly. The Book of History says, "Do not be compliant and submissive to my face, while you criticize me behind my back. "