In the play "Macbeth" by William Shakespeare, when Macbeth says, "We have scorched the snake, not killed it" (line 15), he is metaphorically referring to Banquo's murder and the escape of Banquo's son, Fleance.
This line implies that although they have eliminated Banquo, who was a threat to Macbeth's throne according to the prophecy, the danger is not yet fully eradicated because Fleance, Banquo's son, has escaped. Macbeth sees Fleance's survival as a potential continuation of the threat to his reign, likening it to a snake that has been wounded but not completely eliminated.