Correct
若要人不知，除非己莫为
/ ruò yàorén bùzhī, chúfēi jǐ mò wéi /
Strokes
Definition
If you don't want anyone to know, don't do it (idiom). fig. If you do something bad, people will inevitably hear about it.
Example
Definition
don't do it if you don't want others to know—murder will out; what is done by night appears by day