Warren Buffett stated that the foremost principle shareholders and partners should adhere to is to treat others as you would like to be treated yourself, commonly known as the Golden Rule.

The former CEO described himself as "not a religious person," but he emphasized that no other maxim has held more value over thousands of years than this rule.

"If the whole world followed the Golden Rule, society would be much better off. This principle applies whether you are a parent or a corporate manager," Buffett said in an interview.

He added, "Following this rule costs nothing. In fact, treating people well ultimately benefits you in return. In a way, it's also a form of self-interest, and I have never seen anyone who lives by this principle end up unhappy."