12 And Jonathan said to David, Jehovah, God of Israel, when I sound my father about this time to-morrow, [or] the next day, and behold, there be good toward David, and I then send not to thee, and apprise thee of it, 13 Jehovah do so and much more to Jonathan. Should it please my father [to do] thee evil, then I will apprise thee of it, and send thee away, that thou mayest go in peace; and Jehovah be with thee, as he has been with my father. 14 And thou shalt not only while yet I live shew me the kindness of Jehovah, that I die not, 15 but thou shalt not cut off thy kindness from my house for ever, no, not when Jehovah cuts off the enemies of David, every one from the face of the earth. 16 And Jonathan made [a covenant] with the house of David, [saying,] Let Jehovah even require [it] at the hand of David's enemies! 17 And Jonathan caused David to swear again, by the love he had for 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!