Adam Clarke on 1 Samuel 28:20

Then Saul fell straightway all along on the earth - Literally, he fell with his own length, or with the fullness of his stature. He was so overwhelmed with this most dreadful message, that he swooned away, and thus fell at his own length upon the ground. The woman, being terrified, had probably withdrawn to some distance at the first appearance of the prophet; and Saul was left alone with Samuel. After some short time, the woman came again unto Saul, found him sore troubled, and offered him those succours which humanity dictated.