2 Samuel 15:30

And David went up by the ascent of Mount Olivet, the road which led up past its summit, and wept as he went up, and had his head covered, as the symbol of a sorrowful mind wholly withdrawn from the outer world, and he went barefoot, as a sign of great grief and humiliation; and all the people that was with him, following his example, covered every man his head, and they went up, weeping as they went up. In giving way to a superior force and taking the suffering sent by the Lord upon him, David prepared the way for the salvation of the people. He appears here as a type of Christ, who also entered upon His great suffering by passing over the brook Kidron.