Ecclesiastes 10:8-10

New International Version

⁸ Whoever digs a pit may fall into it;^(A)
    whoever breaks through a wall may be bitten by a snake.^(B)
9 Whoever quarries stones may be injured by them;
    whoever splits logs may be endangered by them.^(C)

¹⁰ If the ax is dull
    and its edge unsharpened,
more strength is needed,
    but skill will bring success.