"Praising the wicked is wrong. " ~~ Talmud, Sota
"It is better that you should not vow than that you should vow and then not pay." ~~ Ecclesiastes (Kohelet) 5:4
"Crime is its own punishment. " ~~ Chaim of Valozhin
"Flee from a sin as from a snake, for if you draw nigh it will bite you! " ~~ Ben Sira 21:2
"False scales are an abomination to the Lord; but a just weight is His delight." ~~ Proverbs (Mishle) 11:1
"Who consorts with the unclean becomes himself unclean; who consorts with clean is cleansed. " ~~ Kelim 12:12
"Who has not savored sin has not been qualified for saintliness. " ~~ Jacob Klatzkin
"A faultless man is possible only in a faultless world." ~~ Hasdai
"Who says, “I shall sin and repent, I shall sin and repent”, repentance will not be vouchsafed him." ~~ Talmud, Yoma
"May my death atone for all my sins!" ~~ Talmud, Berakhot
"The man who steals men’s confidence is the worst of thieves." ~~ Midrash Mekilta Mispatim
"The quintessence of wickedness is foolishness." ~~ The Chofetz Chaim