1 Samuel 18:8

What can he have more but the kingdom? — In this foreboding utterance of Saul there was involved not only a conjecture which the result confirmed, but a deep inward truth: if the king stood powerless before the subjugators of his kingdom at so decisive a period as this, and a shepherd boy came and decided the victory, this was an additional mark of his rejection. — V. Gerlach, quoted in Keil.

Some years had passed since he first heard from the lips of his old prophet-friend the Divine sentence of his rejection from the kingdom. In that sad period he had doubtless been on the look-out for the one destined by the Invisible King to be his successor. This dread expectation of ruin and dethronement had been a powerful factor in the causes which had led to the unhingement of Saul’s mind. Was not this gifted shepherd boy — now the idol of the people — the future hope of Israel?