Sirach 30:8-10

New Revised Standard Version Catholic Edition

⁸ An unbroken horse turns out stubborn,
    and an unchecked son turns out headstrong.
⁹ Pamper a child, and he will terrorize you;
    play with him, and he will grieve you.
¹⁰ Do not laugh with him, or you will have sorrow with him,
    and in the end you will gnash your teeth.