“Be respectful to your superiors, if you have any.”
"Advice to Youth", speech to The Saturday Morning Club, Boston, 15 April 1882. Mark Twain Speaking (1976), ed. Paul Fatout, p. 169 http://books.google.com/books?id=mkFgXWvUkVoC&pg=PA169
Variant: Be respectful to your superiors, if you have any.
Source: The Wit and Wisdom of Mark Twain
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Mark Twain 637
American author and humorist 1835–1910Related quotes

The Analects, The Doctrine of the Mean
Context: Earnest in practicing the ordinary virtues, and careful in speaking about them, if, in his practice, he has anything defective, the superior man dares not but exert himself; and if, in his words, he has any excess, he dares not allow himself such license. Thus his words have respect to his actions, and his actions have respect to his words; is it not just an entire sincerity which marks the superior man?

“Your children don't have to fear you to respect you.”
Attributed

On The Monkees, Pop Chronicles, Show 44 - Revolt of the Fat Angel: Some samples of the Los Angeles sound. (Part 4) http://digital.library.unt.edu/ark:/67531/metadc19808/, interview recorded 8.1.1968 http://web.archive.org/web/20110615153027/http://www.library.unt.edu/music/special-collections/john-gilliland/o-s.

Elliot's Debates, volume 1, p. 463. (29 July 1788)
Variant: Relationship Principle 10
You can tell how much someone respects you by how much he respects your opinion. If he doesn't respect your opinion, he won't respect you.
Source: Why Men Marry Bitches: A Woman's Guide to Winning Her Man's Heart