David swore moreover, and said, Your father knows well that I have found favor in your eyes; and he says, Don't let Jonathan know this, lest he be grieved: but truly as Yahweh lives, and as your soul lives, there is but a step between me and death.
There are several oaths and strong affirmations in this chapter (1 Samuel 20:3; 1 Samuel 20:12-13; 1 Samuel 20:16-17; 1 Samuel 20:23; 1 Samuel 20:42). The one that David made in 1 Samuel 20:3 is very strong. He believed correctly that he was in mortal danger, and he tried to make Jonathan see this. Jonathan was open to anything David wanted to suggest to prove his point (1 Samuel 20:4).