1 Samuel 28:20 - Joseph Benson’s Commentary on the Old and New Testaments

Then Saul fell straightway all along on the earth Struck to the heart, as if the archers of the Philistines had already hit him, at the hearing this dreadful sentence pronounced upon himself, his family, and people; and overcome with astonishment and terror. And was sore afraid because of the words of Samuel Observe, reader, the words of Samuel, says the inspired historian, and not the words of Satan, or any evil spirit personating Samuel. These words, which he now fully believed, and which were the more awful as being pronounced by a departed spirit, sent from the invisible world on purpose to pronounce them, even the spirit of a great and holy prophet, whom he had once highly revered, and to whom, under God, he had owed all his elevation; these words so operated upon his mind, weakened and oppressed with guilt, and upon his body, exhausted with fatigue and fasting, that no strength, or power of motion, was left in him; and he fell at his full length as dead upon the floor. Unhappy Saul! he now reaps the bitter fruits of forsaking God, and of being therefore forsaken by him, and of his many great and aggravated crimes. Vengeance, which had long hovered over him, and waited in long-suffering for his repentance, now advances with large and rapid strides, and his doom approaches. He is deeply sensible of it, and is overwhelmed with horror and dismay on the account thereof.