冰炭不言，冷热自明

Explanation: Metaphor of the sincerity of the heart do not tell the truth, must show in action. 　　Source: "Jin Shu Shen Chuan Wang," Yao and Shun, the Duke of Zhou Zhong admonish those they are able to cause, with its sincere heart who shall also, Bing Tan does not talk, but the quality of hot and cold self-evident who is also its a fact. "