During the Spring and Autumn Period (770-476 BC), numerous dukedoms existed under the Eastern Zhou king, frequently warring for territory. Power struggles within states were also common. A prime example was the murder of the Duke of Wei by his younger brother, Zhou Xu.
Zhou Xu committed the regicide with the help of a high official named Shi Hou and usurped the throne. His subsequent wars brought suffering to the people, causing widespread resentment.
Alarmed by the discontent, Zhou Xu consulted Shi Hou on how to stabilize his rule. Shi Hou suggested seeking help from his father, Shi Que, who was highly esteemed by all.
Shi Que, a former minister who had resigned in protest after the murder, despised both Zhou Xu and his own son for their crime. When Shi Hou came asking for support, Shi Que advised that royal approval from the Zhou king would legitimize Zhou Xu's rule.
Upon being asked how to obtain the king's approval, Shi Que suggested they seek an endorsement from the Duke of Chen, who was trusted by the king and had good relations with Wei.
Zhou Xu and Shi Hou set off for Chen. However, Shi Que secretly sent a fast messenger ahead, urging the Duke of Chen to execute the two murderers.
Upon arrival, the pair were immediately arrested. Officials from Wei came to carry out the execution. They killed Zhou Xu but hesitated over Shi Hou out of respect for his father. Learning of this, Shi Que declared firmly, "My son is also guilty of regicide. What good is he in this world!" He then sent his own man to Chen to behead Shi Hou.
Later historians praised Shi Que: "To safeguard the state's interest, he did not bend the law for his kin. This is truly cutting off consanguinity for righteousness!" Hence originated the idiom "Uphold justice at the cost of one's blood relation."