1 Samuel 28:6 (KJV)

And the Philistines gathered themselves together, and came and pitched in Shunem: and Saul gathered all Israel together, and they pitched in Gilboa.

And when Saul saw the host of the Philistines, he was afraid, and his heart greatly trembled.

And when Saul enquired of the Lord, the Lord answered him not, neither by dreams, nor by Urim, nor by prophets.

Then said Saul unto his servants, Seek me a woman that hath a familiar spirit, that I may go to her, and enquire of her. And his servants said to him, Behold, there is a woman that hath a familiar spirit at En–dor.

And Saul disguised himself, and put on other raiment, and he went, and two men with him, and they came to the woman by night: and he said, I pray thee, divine unto me by the familiar spirit, and bring me him up, whom I shall name unto thee.