Sirach 12:9-11

Revised Standard Version Catholic Edition

⁹ A man’s enemies are grieved when he prospers,
    and in his adversity even his friend will separate from him.
¹⁰ Never trust your enemy,
    for like the rusting of copper, so is his wickedness.
¹¹ Even if he humbles himself and goes about cringing,
    watch yourself, and be on your guard against him;
    and you will be to him like one who has polished a mirror,
    and you will know that it was not hopelessly tarnished.