1 Samuel 28:14

What form? Saul’s questions, together with the woman’s replies, are in themselves evidence that he did not see the apparition himself. Perhaps he was separated from the medium by a curtain, or perhaps he was standing directly before her in the midnight darkness of the cave. When she described the apparition, Saul “perceived that it was Samuel.”

It would be contrary to every principle of righteousness to imagine divine authority being given to a necromancer to summon Samuel from his place of rest. To think that God, who had placed His ban on necromancy (Deut. 18:10-12), would yield to the request of a medium, and disturb His sleeping saint, Samuel, would be wholly inconceivable. But as Satan had the power to appear before Jesus in the wilderness as an angel of light, so he or his agents could, if permitted, also impersonate Samuel, both in form and voice. The devil took this opportunity to taunt Saul with the irony of his fate. The very man who had once persecuted the exponents of this black art was now on his knees before that power, pleading for help.