1 Samuel 20:14 (KJV)

And Jonathan said unto David, O Lord God of Israel, when I have sounded my father about to morrow any time, or the third day, and, behold, if there be good toward David, and I then send not unto thee, and shew it thee;

The Lord do so and much more to Jonathan: but if it please my father to do thee evil, then I will shew it thee, and send thee away, that thou mayest go in peace: and the Lord be with thee, as he hath been with my father.

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

But 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.

So Jonathan made a covenant with the house of David, saying, Let the Lord even require it at the hand of David’s enemies.