若要人不知，除非己莫为

若要人不知，除非己莫为

Literally means:

don't do it if you don't want others to know

Actually means:

what is done by night appears by day

若, if; 己, self; 莫为, not do.

This phrase means that if you don't want others to know, you should not do it. It also means anything wrong that has been committed is bound to be known. It is often used to advise people not to do evil things.

若，如果。己，自己。莫为，不去做。

若要人不知，除非己莫为，要想事人家不知道，除非自己不去做。指做了坏事最后总是会暴露的。多用于劝告人家不要做坏事。