And now, behold, I know well that thou shalt surely be king,.... Not merely by the common report, that he was anointed by Samuel, to which yet he might give credit; but by the providence of God prospering and preserving him, and by his princely spirit and behaviour, and by calling to mind what Samuel had said to him, that his kingdom should be given to a neighbour of his better than he, and so David was by his own confession, 1Sa 24:17; and the cutting off the skirt of his garment might put him in remembrance of the rending of the skirt of Samuel's mantle, upon which he told Saul his kingdom should be rent from him; though some think that was Saul's skirt, and so now he knew thereby, when David cut off his skirt, that the kingdom would be his; and it is a tradition of the Jews , that Samuel said to him at that time, that he that cut off the skirt of his garment should reign after him:and that the kingdom of Israel shall be established in thine hand; and not be rent from him; and yet notwithstanding after this he sought to destroy him.
Midrash Tillim apud Abarbinel.