"The true character of a man is revealed by how he treats people from whom he has nothing to gain." The quote is not exact. Can you help me figure out the exact quote and who said it?

Thank you

The best index to a person's character is (a) how he treats people who can't do him any good, and (b) how he treats people who can't fight back.~Abigail Van Buren ("Dear Abby"), advice columnist

* * *
Since we are destined to live out our lives in the prison of our minds, our one duty is to furnish it well~Peter Ustinov

Dear Abby? Didn't see that comin'.

If I ever use this quote again (now doubtful)I might conveniently leave off the pen name and credit it to Abigail Van Buren.

Thanks for the help and prompt reply.

This is the final test of a gentleman: his respect for those who can be of no possible value to him.
~William Lyon Phelps

If you want to know what a man's like, take a good look at how he treats his inferiors, not his equals.
~J. K. Rowling, Harry Potter and the Goblet of Fire

Thank you for the reply. The concept is on the mark. I'll feel much better about quoting William Lyon Phelps than Dear Abby.