NET
17 Jonathan once again took an oath with David, because he loved him. In fact Jonathan loved him as much as he did his own life.
Darby
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.
KJV
17 And Jonathan caused David to swear again, because he loved him: for he loved him as he loved his own soul.