1 Samuel 28:3-19

Now Samuel had died, and all Israel had mourned for him and buried him in
Ramah, his own city.  Saul had expelled the mediums and the wizards from
the land.  The Philistines assembled, and came and encamped at Shunem.
Saul gathered all Israel, and they encamped at Gilboa.  When Saul saw the
army of the Philistines, he was afraid, and his heart trembled greatly.
When Saul inquired of the LORD, the LORD did not answer him, not by
dreams, or by Urim, or by prophets.  Then Saul said to his servants, "Seek
out for me a woman who is a medium, so that I may go to her and inquire of
her."  His servants said to him, "There is a medium at Endor."

So Saul disguised himself and put on other clothes and went there, he and
two men with him.  They came to the woman by night.  And he said, "Consult
a spirit for me, and bring up for me the one whom I name to you."  The
woman said to him, "Surely you know what Saul has done, how he has cut off
the mediums and the wizards from the land.  Why then are you laying a
snare for my life to bring about my death?"  But Saul swore to her by the
LORD, "As the LORD lives, no punishment shall come upon you for this
thing."  Then the woman said, "Whom shall I bring up for you?"  He
answered, "Bring up Samuel for me."  When the woman saw Samuel, she cried
out with a loud voice; and the woman said to Saul, "Why have you deceived
me?  You are Saul!"  The king said to her, "Have no fear; what do you
see?"  The woman said to Saul, "I see a divine being coming up out of the
ground."  He said to her, "What is his appearance?"  She said, "An old man
is coming up; he is wrapped in a robe."  So Saul knew that it was Samuel,
and he bowed with his face to the ground, and did obeisance.

Then Samuel said to Saul, "Why have you disturbed me by bringing me up?"
Saul answered, "I am in great distress, for the Philistines are warring
against me, and God has turned away from me and answers me no more, either
by prophets or by dreams; so I have summoned you to tell me what I should
do."  Samuel said, "Why then do you ask me, since the LORD has turned from
you and become your enemy?  The LORD has done to you just as he spoke by
me; for the LORD has torn the kingdom out of your hand, and given it to
your neighbor, David.  Because you did not obey the voice of the LORD, and
did not carry out his fierce wrath against Amalek, therefore the LORD has
done this thing to you today.  Moreover the LORD will give Israel along
with you into the hands of the Philistines; and tomorrow you and your sons
shall be with me; the LORD will also give the army of Israel into the
hands of the Philistines."