The general meaning is: Jonathan had a presentiment, doubtless from God, that David would be established upon the throne. By God’s mercy he had the comfort, which he well deserved, of knowing that his own posterity would receive kindness at David’s hand (see the marginal references).
Related Commentaries of 1 Samuel 20:14
1 Samuel 20:14-15
14 And thou shalt not only while yet I live shew me the kindness of the LORD, that I die not:
15 But also thou shalt not cut off thy kindness from my house for ever: no, not when the LORD hath cut off the enemies of David every one from the face of the earth.