1 Samuel 20:12-17 New International Version (NIV)
12 Then Jonathan said to David, “I swear by the Lord, the God of Israel, that I will surely sound out my father by this time the day after tomorrow! If he is favorably disposed toward you, will I not send you word and let you know? 13 But if my father intends to harm you, may the Lord deal with Jonathan, be it ever so severely, if I do not let you know and send you away in peace. May the Lord be with you as he has been with my father. 14 But show me unfailing kindness like the Lord’s kindness as long as I live, so that I may not be killed, 15 and do not ever cut off your kindness from my family—not even when the Lord has cut off every one of David’s enemies from the face of the earth.”
16 So Jonathan made a covenant with the house of David, saying, “May the Lord call David’s enemies to account.” 17 And Jonathan had David reaffirm his oath out of love for him, because he loved him as he loved himself.