" If it is not right, do not do it;

if it is true, do not say it."

This saying it is better to not say a lie and hurt someone later.

Even if its bad its better to tell them the truth. An example is secret doing. When people  tell you a secret is because they trust on you to not say nothing why because they believe you. However thats whynyou shouldnt say anythimg because if you then tose people are never gonna tell you a secret again, why becausethey trusted you on not saying anything but you just had to open the mouth. This why i think this qoute is talking about.

MARCUS AURELIUS