"The Torah teaches incidentally good manners." ~~ Ishmael b. Elisha
"You shall rise before the aged and show deference to the old." ~~ Leviticus (Vayikra) 19:32
"Never enter a neighbor’s house unwarned." ~~ Derekh Eretz R.
"Who eats even plain bread and salt with his friend should be grateful to him." ~~ Tanna Deve Eliyahu R.
"Interrupt not the speech of your friend before he finish!" ~~ Hidden Scrolls
"In the midst of a discourse, speak not." ~~ Apocrypha: Ben Sira
"My son, answer not before you hear, nor speak in the midst of converse!" ~~ Ben Sira 11:8
"Too honor an old man one should not sit in his place or contradict his words." ~~ Rashi
"Be not boastful in your speech! " ~~ Ben Sira 4:32
"There is no truer index to intelligence than the way one acts at the table." ~~ Ibn Gabirol
"Insulting one’s senior is not the same as insulting one’s junior." ~~ Talmud, Ketubot
"Manners provide the lubrication without which frictions would develop." ~~ Rabbi Edgar Magnin