12 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? 13 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. 14 And thou shalt not only while yet I live show me the lovingkindness of Jehovah, that I die not; 15 but also thou shalt not cut off thy kindness from my house for ever; no, not when Jehovah hath cut off the enemies of David every one from the face of the earth. 16 So Jonathan made a covenant with the house of David, [saying], And Jehovah will require it at the hand of David's enemies. 17 And Jonathan caused David to swear again, for the love that he had to him; for he loved him as he loved his own soul.
Matthew Henry's Commentary on 1 Samuel 20:12-17
Commentary on 1 Samuel 20:11-23
(Read 1 Samuel 20:11-23)
Jonathan faithfully promises that he would let David know how he found his father affected towards him. It will be kindness to ourselves and to ours, to secure an interest in those whom God favours, and to make his friends ours. True friendship rests on a firm basis, and is able to silence ambition, self-love, and undue regard for others. But who can fully understand the love of Jesus, who gave himself as a sacrifice for rebellious, polluted sinners! how great then ought to be the force and effects of our love to him, to his cause, and his people!