From the Bible:
Gospel of St. Matthew, Chapter 7:
Give not that which is holy unto dogs, neither cast ye your pearls before swine, lest they trample them under their feet, and turn again and rend you.
From the Bhagavad Gita, eighteenth Chapter:
Never speak of these truths to one who is without self-control or devotion, who renders no service, who does not care to hear, or who speaks ill of Me.