precept
n
1 [C] rule or guide, esp for behaviour 规范; 准则; (尤指)格言, 箴言
follow the precepts of one´s religion 遵循自己的宗教戒律
He lived by the precept `practise what you preach´. 他奉行`言行一致'的准则.
2 [U] moral instruction 道德箴言; 教训
Example is better than precept. 身教胜於言教.