precept
/ˈpri:sept; `prisɛpt/ 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.