《逸周书·卷七·官人解》
忠心以侍奉父母，愉快地敬奉，尽其力而不表露，敬奉父母使之安泰，叫做忠孝者。
中忠爱以事亲，欢以尽力而不回，敬以尽力而不□，曰忠孝者也。
Serving one's parents with loyalty, honoring them with joy, doing one's best without showing it, honoring one's parents so that they are at ease, is called being loyal and filial.