20:17 Swear again - Heb. and Jonathan added or proceeded to make David swear; that is, having himself sworn to David or adjured David, in the foregoing verse , he here requires David's oath to him, by way of restipulation or confirmation. Loved him - Because he had a true friendship for David, he desired that the covenant might be inviolably observed through all their generations.
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!
