How is my title? I was overjoyed when it came to my mind.

Ok, today I am going to introduce a Chinese proverb to my American friends here.

害人之心不可有，防人之心不可无。

（hai ren zhi xin bu ke you, fang ren zhi xin bu ke wu.）

My father told me to keep this in mind when I first left them for Shanghai to start my new life all by myself at the age of 15.

It means that you can never have the intention to harm others, but you should always be cautious enough to avoid being harmed by others.

The latter half is the real point in this proverb. So some authorities translated it as below.

Honesty must be based on security. 

I have another idea but I don't know which would make more sense to a native English speaker.Here it is. 

Harm no one. Be harmed by no one.

Ok. Stay happy and stay safe!