Genesis 32:26

Let me go. The Angel sought to withdraw before daybreak, but gave no reason for wishing to do so. Commentators have suggested a desire on His part either to prevent others from witnessing the scene or perhaps to prevent Jacob from seeing Him.

I will not let thee go. The crippling touch and the divine voice had convinced Jacob that the One with whom he had thus wrestled for hours was a messenger from heaven. Having for hours sought desperately for divine help, Jacob felt he could not afford to let Him go without first receiving assurance of the pardon and protection for which he longed. This he asked as an outright gift, realizing that he had nothing to offer God in return. He proposed no bargain; his desperate situation was his only plea. The help he needed could come only from God. For the first time in his life he knew his own resources to be inadequate. From his birth, when he had caught his brother by the heel, to his last years in Haran, when he had outwitted his uncle Laban (Hosea 12:3, 4), Jacob had approached the solution of life’s problems by questionable methods of his own devising. He was now a changed man. Whereas in the past he had relied upon his own wisdom and strength, he had now learned to trust wholly in God.