如臂使指

From Jia Yi's Discourse on Public Security:

令海內之勢如身之使臂，臂之使指，莫不制從，諸侯之君不敢有異心，輻湊並進而歸命天子。 [Classical Chinese, trad.]

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令海内之势如身之使臂，臂之使指，莫不制从，诸侯之君不敢有异心，辐凑并进而归命天子。 [Classical Chinese, simp.]

From: c. 174 BCE, 賈誼,《陳政事書》

Lìng hǎinèi zhī shì rú shēn zhī shǐ bì, bì zhī shǐ zhǐ, mòbù zhìcóng, zhūhóu zhī jūn bùgǎn yǒu yìxīn, fúcòu bìng jìn ér guīmìng tiānzǐ. [Pinyin]

Thus the situation of the whole land will be as though the body handles the arms and the arms control the fingers with no one disobeying the command. The vassal kings would not even dare to think of rebellion, and all submit to the Son of Heaven like spokes to a wheel.

Alternatively, from Guanzi:

若此，則如胷之使臂，臂之使指也。 [Traditional Chinese poetry, trad.]
若此，则如胸之使臂，臂之使指也。 [Traditional Chinese poetry, simp.]

From: Guanzi, 5^th century BCE to 220 CE

Ruò cǐ, zé rú xiōng zhī shǐ bì, bì zhī shǐ zhǐ yě. [Pinyin]

This being the case, these feudatories and fiefs can be controlled like a chest controlling the arms or arms handling fingers.

如臂使指

1. to control or handle someone or something effectively and easily; to be in perfect command of