go by the book/do something by the book idiom
C2 照规矩办事
to do something exactly as the rules tell you
My lawyer always goes strictly by the book. 我的律师一贯严守规矩办事。
This is a private deal - we don't have to do everything by the book. 这是笔私下的交易——我们没必要办什么事都循规蹈矩。