1 Samuel 20:12-13

12Then Jonathan said to David, ‘I make this promise to you, and the Lord, Israel's God, knows that it is true. Tomorrow or the next day I will find out what my father is thinking about you. If he is feeling friendly to you, I will send someone to tell you.

13But if my father wants to hurt you, I will tell you clearly. I ask the Lord to punish me, if I do not tell you. I will help you to escape and be safe. I pray that the Lord will bless you, as he blessed my father.