These three questions mean basically the same thing. David uses them to emphasize that he has done nothing wrong to Saul. This rhetorical question can be translated as a statement. AT: "I have done nothing wrong. I have not committed any iniquity. I have not sinned against your father. He has no reason to take my life." (See: [[rc://en/ta/man/translate/figs-parallelism]] and [[rc://en/ta/man/translate/figs-rquestion]])