过河拆桥 — “Cross the river and demolish the bridge”

The idiom "过河拆桥" (guò hé chāi qiáo) originates from a story in the Yuan Dynasty, recorded in 'The History of Yuan' (元史), specifically the biography of Che Li Tie Mu Er.

Che Li Tie Mu Er, a capable minister, observed the corruption and expense of the imperial examination system while serving in Zhejiang. He resolved to abolish it once he gained more power. Later, as a high-ranking official (中书平章政事), he successfully petitioned Emperor Shun to abolish the system, a decision that caused great controversy. Though many opposed, the emperor supported Che Li Tie Mu Er.

When the imperial edict to abolish the examinations was about to be issued, another high-ranking official, Xu You Wang (许有王), who had himself risen through the examination system, vehemently opposed it. However, his protests were in vain. On the day the edict was to be read, all officials were summoned. Xu You Wang was intentionally placed at the very front of the assembly, a humiliating position for an opponent.

After the reading, as a disheartened Xu You Wang was leaving, a censor named Puhua (普化) approached him and sarcastically remarked, "You, Canzheng (a title for Xu You Wang), are truly someone who crosses the river and demolishes the bridge now." Puhua's taunt implied that Xu You Wang, having benefited greatly from the imperial examination system to attain his position, was now symbolically 'demolishing the bridge' by being seen as a leading figure in its abolishment. This left Xu You Wang feeling shamed and resentful, leading him to feign illness and withdraw from court.