Charles Ellicott Commentary 1 Samuel 20:17

"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." — 1 Samuel 20:17 (ASV)

And Jonathan caused David to swear again. —Throughout this touching interview, it is the prince who appears as the suppliant for the outlaw’s future kind services. Jonathan—looking forward with absolute certainty to the day when his persecuted friend would be on the throne, and he in his grave—dreaded for his own fatherless children the fate which all too probably awaited them, as it had been a common custom in all ages in the East, when the dynasty was violently changed, to put to death the children and near relations of the former king.