Wu Chengsi
However, Pei would soon begin to run afoul of Empress Dowager Wu. Later in 684, pursuant to suggestions by her nephew Wu Chengsi, Empress Dowager Wu planned to posthumously honor her ancestors princes, and also build seven ancestral temples for them—a highly sensitive move, in that regulations allowed only the emperor to build seven ancestral temples, while any noble family, no matter how honored, was restricted to no more than five temples. Pei argued against the move, specifically comparing Empress Dowager Wu's actions to those of Emperor Gao of Han's wife Empress Lü Zhi (whose clan was powerful in her lifetime as empress dowager but was slaughtered after her death), to no avail, and she began to view him negatively from that point on. Their conflict became worsened later that year, as Empress Dowager Wu, listening to Wu Chengsi's advice, began considering seizing the throne herself with the title of "emperor." She, Wu Chengsi, and another powerful nephew Wu Sansi were all concerned about the high esteem the people held for Emperor Ruizong's granduncles Li Yuanjia (李元嘉) the Prince of Han and Li Lingkui (李靈夔) the Prince of Lu, and Wu Chengsi suggested that she find excuses to have them executed. When Empress Dowager Wu consulted the chancellors, both Liu Yizhi and Wei Siqian were fearful and therefore did not dare to speak, but Pei strenuously objected, making her even more angry at him.