I Samuel 20:11-13

And Jonathan said to David, “Come, let us go out into the field.” So both of them went out into the field. Then Jonathan said to David: “The LORD God of Israel is witness! When I have sounded out my father sometime tomorrow, or the third day, and indeed there is good toward David, and I do not send to you and tell you, may the LORD do so and much more to Jonathan. But if it pleases my father to do you evil, then I will report it to you and send you away, that you may go in safety. And the LORD be with you as He has been with my father.