David uses a question to rebuke Abner for not guarding Saul. AT: "You are the greatest soldier in Israel." (See: [[rc://en/ta/man/translate/figs-rquestion]])
Possible meanings are 1) this is a real question and David wants Abner to answer him or 2) this is a rhetorical question and David is rebuking Abner. AT: "Therefore you should have kept watch over your master the king!" (See: [[rc://en/ta/man/translate/figs-rquestion]])