《三国志·蜀书·杜周杜许孟来尹李谯郤》
说的就是圣人知天命而不勉强而为，所以尧舜因为自己的儿子德行浅薄，知道上天有所授命，就寻求天下能授予的人，他们的儿子虽然不贤，但灾祸还没萌发，而把天下让给上天认可之人，祸患还会产生吗？
言圣人知命而不苟必也。故尧、舜以子不善，知天有授，而求授人；子虽不肖，祸尚未萌，而迎授与人，况祸以至乎！
The meaning is that a sage knows the will of Heaven and does not try to force things. Therefore, Yao and Shun, because their own sons were not virtuous enough, knew that Heaven had a mandate, and they looked for someone in the world to whom they could pass on the mandate. Although their sons were not virtuous, the disaster had not yet sprouted, and by giving the world to someone recognized by Heaven, would the disaster still happen?