探囊取物 — “To accomplish something with extreme ease”

Han Xizai was a renowned talent during the Southern Tang period in the Five Dynasties. Because Emperor Mingzong Li Siyuan had killed his father, he decided to leave the Central Plains and seek refuge in the Southern Tang regime in Jiangnan.

Han Xizai's close friend Li came to see him off. Before his departure, Han Xizai told Li, "If Southern Tang values me and appoints me as prime minister, I will surely lead an army north and swiftly recover the Central Plains." Li, upon hearing this, replied, "If I were to serve as prime minister in a Central Plains state, I would be able to effortlessly seize the states of Southern Tang, as easy as taking something out of my pocket." (This is where the idiom's meaning comes from).

Soon after Han Xizai defected to Southern Tang, Southern Tang annexed the state of Wu. However, due to the emperor's incompetence and the prevalence of treacherous officials, Han Xizai was never given significant responsibilities or appointed as prime minister. Meanwhile, his friend Li became a great general in a Central Plains state – the Later Zhou. He was ordered to conquer Southern Tang, achieved numerous meritorious deeds, capturing many cities from Southern Tang, and was highly regarded by the Later Zhou court. Although he never became prime minister to fulfill his own vow, his circumstances were clearly much better than Han Xizai's.