C. F. Keil and Franz Delitzsch on 1 Samuel 20:8

1Sa 20:8

David made sure that Jonathan would grant this request on account of his friendship, as he had brought him into a covenant of Jehovah with himself. David calls the covenant of friendship with Jonathan (1Sa 18:3) a covenant of Jehovah, because he had made it with a solemn invocation of Jehovah. But in order to make quite sure of the fulfilment of his request on the part of Jonathan, David added, “But if there is a fault in me, do thou kill me (אתּה used to strengthen the suffix); for why wilt thou bring me to thy father?” sc., that he may put me to death.