Proverbs 30:10-12

New Revised Standard Version Catholic Edition

¹⁰ Do not slander a servant to a master,
    or the servant will curse you, and you will be held guilty.

¹¹ There are those who curse their fathers
    and do not bless their mothers.
¹² There are those who are pure in their own eyes
    yet are not cleansed of their filthiness.