Jamieson, Fausset and Brown on Ecclesiastes 10:8

8. The fatal results to kings of such an unwise policy; the wrong done to others recoils on themselves (Ec 8:9); they fall into the pit which they dug for others (Es 7:10; Psa 7:15; Pr 26:27). Breaking through the wise fences of their throne, they suffer unexpectedly themselves; as when one is stung by a serpent lurking in the stones of his neighbor's garden wall (Psa 80:12), which he maliciously pulls down (Am 5:19).