C. F. Keil and Franz Delitzsch on 1 Samuel 24:19

1Sa 24:19

“If a man meet with his enemy, will he send him (let him go) in peace?” This sentence is to be regarded as a question, which requires a negative reply, and expresses the thought: When a man meets with an enemy, he does not generally let him escape without injury. But thou hast acted very differently towards me. This thought is easily supplied from the context, and what follows attaches itself to this: “The Lord repay thee good for what thou hast done to me this day.”