1 Samuel 20:30-34 NIV

30 Saul's anger flared up at Jonathan and he said to him, "You son of a perverse and rebellious woman! Don't I know that you have sided with the son of Jesse to your own shame and to the shame of the mother who bore you?
31 As long as the son of Jesse lives on this earth, neither you nor your kingdom1 will be established. Now send and bring him to me, for he must die!"

References for 1 Samuel 20:31

32 "Why2 should he be put to death? What3 has he done?" Jonathan asked his father.

References for 1 Samuel 20:32

33 But Saul hurled his spear at him to kill him. Then Jonathan knew that his father intended4 to kill David.

References for 1 Samuel 20:33

34 Jonathan got up from the table in fierce anger; on that second day of the month he did not eat, because he was grieved at his father's shameful treatment of David.