In English-speaking traditionally-Christian cultures, this is called "the Golden Rule." Versions of the Golden Rule exist in all the major world religions. When used by English speakers, it refers to a phrase often quoted as
"Do unto others as you would have them do unto you."
It appears twice in the New Testament, the Christian part of the Bible: Luke 6:31 and Matthew 7:12. In the traditional English translation called the "King James Version," which uses old-fashioned English, it is:
"And as ye would that men should do to you, do ye also to them likewise."
It means that if you want other people to tell you the truth, you should always tell the truth to other people. If you want other people to respect you, you should respect other people.
An important detail is that it is based on what you _want_ from other people. If you want other people to tell you the truth, the Golden Rule says you should always tell the truth. It does not guarantee that if you tell the truth to other people, other people will tell you the truth. And it does not give you permission to lie just because other people lie to you. If someone lies to you, it is still the case that you _wanted_ them to tell you the truth, and therefore you yourself must tell them the truth.