Now Jonathan again caused David to vow, because he loved him; for he loved him as he loved his own soul.
1 Samuel 20:17
Surrounding context
20:16 So Jonathan made a covenant with the house of David, saying, "Let the LORD require it at the hand of David's enemies."
20:17 Now Jonathan again caused David to vow, because he loved him; for he loved him as he loved his own soul.
20:18 Then Jonathan said to David, "Tomorrow is the New Moon; and you will be missed, because your seat will be empty.