1 Samuel 20:12-15

12And Jonathan said unto David, The LORD, the God of Israel, be witness; when I have sounded my father about this time tomorrow, or the third day, behold, if there be good toward David, shall I not then send unto thee, and disclose it unto thee?

13The LORD 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 the LORD be with thee, as he hath been with my father.

14And thou shalt not only while yet I live shew me the kindness of the LORD, that I die not:

15but also thou shalt not cut off thy kindness from my house for ever: no, not when the LORD hath cut off the enemies of David every one from the face of the earth.