Dāng lǐngdǎo de děi dǒng yǎnglǎomǎ de dàolǐ, bù néng yòng wán jiù diū.
A leader should understand 'looking after the old horse' — you can't just use people up and discard them.
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From 《韩诗外传》: the noble Tian Zifang saw an old horse abandoned on the road and bought it back, saying a benevolent man would not discard those who gave their strength. Used ever since as the ethic of caring for loyal servants past their prime.