1 Samuel 20:3
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.
The saying belongs to the time after David slew Goliath, when Saul kept David with him and would not let him return to his father's house. Then the soul of Jonathan was knit with the soul of David, and Jonathan loved him as his own soul. Jonathan and David made a covenant to be united as brethren, and Jonathan gave David his robe and his garments, even his sword and his bow and his girdle. At that time David was entrusted with important responsibilities and won affection by modesty. It is part of the account in which Jonathan's bond with David helps preserve David's life while Saul seeks to kill him.
In the verse David speaks to Jonathan with intense earnestness out of a wounded heart and with a longing to see his friend once more. He is conscious of his own innocence, yet has little confidence in Saul's assurance of peace, for fear the king's mood will change as before. Jonathan, by contrast, believed Saul had changed his purpose and would do nothing great or small without telling him. After the remarkable exhibition of God's power he could not believe Saul would still harm David, since that would be open rebellion against God. Unconvinced, David declared as fact that death was immediately close, with only a single step between him and death.