芒刺在背 — “To feel extremely uneasy”

After Emperor Wu of Han died in 87 BC, his youngest son, Liu Fuling, who was only 8 years old, ascended the throne, known historically as Emperor Zhao of Han. According to Emperor Wu's will, Grand Marshal and General-in-Chief Huo Guang, along with Imperial Censor Sang Hongyang and others, assisted in governing, wielding significant military and political power in the court. Emperor Zhao did not live long and died at the age of 21. He had no son, so Huo Guang enthroned Liu He, Emperor Wu's grandson, as the emperor.

Later, Huo Guang discovered that Liu He led a dissolute life, constantly indulging in pleasure-seeking. After consulting with the ministers, he deposed Liu He and established Liu Xun, Emperor Wu's great-grandson, as emperor. This was Emperor Xuan of Han. However, Liu Xun was also very clear that Huo Guang wielded immense power, and his own life and fate as emperor were entirely dependent on him, making him deeply fearful.

One of the major events after Liu Xun's ascension was to visit the ancestral temple. On that day, Emperor Xuan rode in an elaborately decorated carriage, with Huo Guang sitting beside him as an escort. The Emperor, seeing Huo Guang's imposing stature and stern expression, involuntarily felt a deep sense of awe and profound uneasiness, as if thorns were pricking his back. Thereafter, Emperor Xuan was always extremely cautious when in Huo Guang's presence.

In 68 BC, Huo Guang died of illness. With him no longer accompanying him in the carriage, Emperor Xuan finally felt completely unburdened and free to act.