“Far from it!” Jonathan replied. “You will not die. Indeed, my father does nothing, great or small, without telling me. So why would he hide this matter from me? This cannot be true!”
Here, I. David makes a representation to Jonathan of his present troubles. While Saul lay bound by his trance at Naioth David escaped to the court, and got to speak with Jonathan. And it was happy for him that he had such a friend at court, when he had such an enemy on the throne.
Commenting on 1 Samuel 20:1-8
And he said unto him, God forbid, thou shalt not die,.... He could not believe his father had any such intention; and that if he discovered anything of that kind, it was only when he was in a frenzy, and a melancholy disorder had seized him; and that David had nothing to fear on that head, and that he would secure him from all danger...
My father will do nothing - Jonathan thought that his father could have no evil design against David, because of the oath which he had sworn to himself Sa1 19:6; and at any rate, that he would do nothing against David without informing him.