Yu Cong (于琮; died 881), courtesy name Liyong (禮用), was an official of the Chinese Tang dynasty, serving as a chancellor during the reign of his brother-in-law Emperor Yizong.
Zheng made the comment to Yu:[1] You, young man, have much talent, but as you do not pay attention to details, you are put down in your reputation, and therefore you are stuck in your position.
[1] This appeared to coincide with a record in the Zizhi Tongjian that showed that in 859, Yu was promoted from the position of copyeditor (校書郎, Xiaoshu Lang) at the Palace Library to be Zuo Shiyi (左拾遺), a low-level advisory official at the examination bureau of government (門下省, Menxia Sheng).
In 872, Yu was therefore sent out of the capital to serve as the military governor (jiedushi) of Shannan East Circuit (山南東道, headquartered in modern Xiangfan, Hubei), but just three months later, he was further demoted to be the titular teacher of Emperor Yizong's son Li Yan the Prince of Pu, but with his office at the eastern capital Luoyang.
Princess Guangde chose to accompany him to Shao Prefecture and, during the entire journey, she kept a close watch on him; it was said that it was only because of this that Yu was not murdered.
[5] At a later point, he was recalled to Chang'an to serve as You Pushe (右僕射), one of the heads of the executive bureau (尚書省, Shangshu Sheng).
Huang, insulted, fiercely sieged Guang Prefecture and captured it, killing the military governor Li Tiao (李迢).
[6] By 880, Huang had returned to central China and, with Tang forces sent to stop him collapsing on their own, headed directly for Chang'an.