David uses the word "flea" as a metaphor for a person, himself, who cannot do any great harm. Alternate translation: "this single flea" or "me, and I cannot harm you any more than one flea can" (See: [[rc://en/ta/man/jit/figs-metaphor]])
Saul is chasing David as if he were hunting a valuable wild bird. (See: [[rc://en/ta/man/jit/figs-simile]] and [[rc://en/ta/man/jit/translate-unknown]])