Charles Ellicott Commentary 1 Samuel 13:14

"But now thy kingdom shall not continue: Jehovah hath sought him a man after his own heart, and Jehovah hath appointed him to be prince over his people, because thou hast not kept that which Jehovah commanded thee." — 1 Samuel 13:14 (ASV)

Now your kingdom shall not continue. —The succession was thus formally transferred elsewhere.

Still, when the words of doom were spoken by the prophet, David, the son of Jesse—the man after God’s own heart—could at that time have been only a mere child.

Had King Saul repented of what he had done, he might have been forgiven, “for God’s threats, like His promises, are conditional. There is no fatalism in the Bible, but a loving discipline for humanity’s recovery. But behind it stands the Divine foreknowledge and omnipotence, and so to the prophetic view Saul’s refusal to repent, his repeated disobedience, and the succession of David were all revealed as accomplished facts.” — Dean Payne Smith.