in Salome by Oscar Wilde : what this sentences refer to? "do not rejoice, all you Philistines, that the rod that struck you is broken; from the root of that snake will spring up a viper, its fruit will be a darting, venomous serpent."

This quote comes directly from the Bible, Isaiah 14:29-32. It refers to the prophecy, which warns that a cockatrice will come from the serpents root (the kings who had been killed) to punish them further and destroy their nation (the nation of the Philistines).