1 Samuel 20:12-17

Then Jonathan said to David, “The LORD, the God of Israel, is my witness! When I have sounded out my father about this time tomorrow, or the third day, behold, if he has a good feeling toward you, shall I not then send word to you and make it known to you? But if it pleases my father to do you harm, may the LORD do so to Jonathan, and more if I do not let you know about it and send you away, so that you may go in safety. And may the LORD be with you as He has been with my father. If I am still alive, will you not show me the lovingkindness and faithfulness of the LORD, so that I will not die? You shall never cut off your lovingkindness and faithfulness from my house, not even when the LORD cuts off every one of the enemies of David from the face of the earth.” So Jonathan made a covenant with the house of David. [He added,] “May the LORD require it at the hands of David’s enemies. [that is, hold them accountable for any harm they inflict on David].” Jonathan made David vow again because of his love for him, for Jonathan loved him as himself.