韬光养晦 To hide one’s abilities and keep them out of view. The Handian dictionary cites a Qing novel: “You must hide your light, and then watch the timing of heaven.”
In Chinese foreign policy, the phrase is linked to Deng Xiaoping’s guidance around 1990. Sources differ on the exact wording of his formula and on when he first used it. The Selected Works of Deng Xiaoping record a related line: “We must never take the lead. This is a basic state policy.”