《旧唐书·列传·卷九十》
行至阳，遇见朱氵此的家奴苏玉正要到韦皋那里去，苏玉对牛云光说： 太尉已登上了皇帝宝座，派我持诏书前去任命韦皋为御史中丞，你可率兵返回陇州。
行及汧阳，遇泚家僮苏玉将使于皋所，苏玉谓云光曰： 太尉已登宝位，使我持诏以韦皋为御史中丞，君可以兵归陇州。
When he arrived at Yang County, he met Zhu Cui’s family slave Su Yu who was about to go to Wei Gao’s place, Su Yu said to Niu Yunguag: The Grand Commander has ascended to the throne, sent me to deliver an edict to appoint Wei Gao to be the Imperial Censor of the Central Secretariat, you can lead troops to return to Long Prefecture.