Sirach 19:27-29

New Revised Standard Version Catholic Edition

²⁷ He hides his face and pretends not to hear,
    but when no one notices, he will take advantage of you.
²⁸ Even if lack of strength keeps him from sinning,
    he will nevertheless do evil when he finds the opportunity.
²⁹ A person is known by his appearance,
    and a sensible person is known when first met, face to face.