From
《论语·学而》 (Analects, Book I, c. 500 BCE):
不患人之不己知,
患不知人也 (Do not worry that others do not know you; worry that you do not know others). Confucius restates this idea multiple times in the Analects (the
里仁,
卫灵公 chapters too), one of his core teachings on humility and self-focus.