Ecclesiastes 10:8-11

He who digs a pit [for others] may fall into it, and a serpent may bite him who breaks through a [stone] wall. [Ps 57:6] He who quarries stones may be hurt with them, and he who splits logs may be endangered by them. [Prov 26:27] If the axe is dull and he does not sharpen its edge, then he must exert more strength; but wisdom [to sharpen the axe] helps him succeed [with less effort]. If the serpent bites before being charmed, then there is no profit for the charmer.