金光明經文句記 5.218

5.218

初、述意。佛經釋天子義，此文最顯。若儒教則云王者父天母地，為天子之故。《援神契》曰「天覆地載謂之天子。」

First, stating the intention. As for the Buddhist sūtras explaining the meaning of "Son of Heaven", this passage is the most explicit. In Confucianism, it is said that the ruler takes Heaven as father and Earth as mother, which is why he is the Son of Heaven. The Yuanshenqi says: "Being covered by Heaven and borne by Earth is called being the Son of Heaven."