3 But David took an oath and said, “Your father knows very well that I have found favor in your eyes, and he has said to himself, ‘Jonathan must not know this or he will be grieved.’ Yet as surely as the LORD lives and as you live, there is only a step between me and death.”

Read 1 Samuel 20:3 Using Other Translations

And David sware moreover, and said, Thy father certainly knoweth that I have found grace in thine eyes; and he saith, Let not Jonathan know this, lest he be grieved: but truly as the LORD liveth, and as thy soul liveth, there is but a step between me and death.
But David vowed again, saying, "Your father knows well that I have found favor in your eyes, and he thinks, 'Do not let Jonathan know this, lest he be grieved.' But truly, as the LORD lives and as your soul lives, there is but a step between me and death."
Then David took an oath before Jonathan and said, “Your father knows perfectly well about our friendship, so he has said to himself, ‘I won’t tell Jonathan—why should I hurt him?’ But I swear to you that I am only a step away from death! I swear it by the LORD and by your own soul!”