1 Samuel 20:30-33

30Saul became very angry with Jonathan. He said, ‘You stupid man! I see that you have turned against me! You have become a friend of that son of Jesse. You have brought shame on yourself. Your mother should be ashamed that she gave birth to you!

31You will never rule as king while that son of Jesse is still alive. Send men to go and bring him to me now. He must die!’

32Jonathan said to his father, King Saul, ‘Why must David die? What wrong thing has he done?’

33Then Saul threw his spear at Jonathan and tried to kill him. So Jonathan knew that his father had decided to kill David.