1 Samuel 20:32-34

32Jonathan answered Saul his father, “Why must he be put to death? What has he done?”

33Then Saul hurled his spear at him to strike him down, so Jonathan knew [without any doubt] that his father had decided to put David to death.

34Then Jonathan stood up from the table in the heat of anger, and ate no food on that second day of the new moon (month), for he grieved and worried about David because his father had dishonored him.