About This Teaching
Ajahn Chah describes how he once watched another monk's behaviour and became upset. He suffered, while the other monk did not, because he was watching the outside.
Later he learned that appearances mislead: some people drive fast but carefully, while others drive slowly and have many accidents. So he advises not clinging to rules and outer forms. His measure for proper practice is to watch others no more than ten percent of the time and watch oneself ninety percent.