Ecclesiastes 10:8-10

New Revised Standard Version, Anglicised

⁸ Whoever digs a pit will fall into it;
    and whoever breaks through a wall will be bitten by a snake.
⁹ Whoever quarries stones will be hurt by them;
    and whoever splits logs will be endangered by them.
¹⁰ If the iron is blunt, and one does not whet the edge,
    then more strength must be exerted;
    but wisdom helps one to succeed.