Song Jing
In 704, when Cui was still serving as deputy minister of civil service affairs, he was given the designation "Tong Fengge Luantai Pingzhangshi" (同鳳閣鸞臺平章事), making him a chancellor "de facto". By late that year, when Wu Zetian was ill and was often attended only by her lovers Zhang Yizhi and Zhang Changzong, Cui made the suggestion to her that she should have her sons Li Xian the Crown Prince and Li Dan the Prince of Xiang attend to her—not members of other clans (i.e., not the Zhang brothers). Wu Zetian, while thanking him for his input, paid no heed. Cui later supported the imperial censor Song Jing in Song's attempt to investigate Zhang Changzong for corruption and plotting treason, but Wu Zetian did not permit the investigation. She did, however, approve a petition jointly submitted by him and Li Jiao and supported by Huan Yanfan that the people who were found guilty and executed due to accusations by her secret police officials (such as Zhou Xing and Lai Junchen) early in her reign be posthumously restored to honor.