1 Samuel 20:11-13

And Jonathan said unto David, Come, and let us go out into the field. And they went out both of them into the field. And Jonathan said unto David, Jehovah, the God of Israel, be witness: when I have sounded my father about this time to-morrow, or the third day, behold, if there be good toward David, shall I not then send unto thee, and disclose it unto thee? Jehovah do so to Jonathan, and more also, should it please my father to do thee evil, if I disclose it not unto thee, and send thee away, that thou mayest go in peace: and Jehovah be with thee, as he hath been with my father.