Book 15: 《衛靈公》 Wei Ling Gong (Duke Ling of Wey)
《衛靈公》 Passage 15.10
子貢問為仁。子曰：「工欲善其事，必先利其器。居是邦也，事其大夫之賢者，友其士之仁者。」
Legge Translation (1861)
Zigong asked about the practice of virtue. The Master said: "The mechanic, who wishes to do his work well, must first sharpen his tools. When you are living in any State, take service with the most worthy among its great officers, and make friends of the most virtuous among its scholars."