《资治通鉴·唐纪·唐纪二十六》
张说又指使殿中监姜皎向唐玄宗进言道： 陛下早就想任命一位河东总管，却苦于找不到合适的人选，臣现在发现了这样一位称职的人。 
又使殿中监姜皎言于上曰： 陛下常欲择河东总管而难其人，臣今得之矣。 
Zhang Shuo again instigated Jiang Jiao, the Palace Supervisor, to advise Emperor Xuanzong of Tang, "Your Majesty has long thought of appointing a Governor of Hedong, but you have struggled to find a suitable candidate. I have now found such a competent person."