וַיֹּ֨אמֶר שָׁא֜וּל לַעֲבָדָ֗יו בַּקְּשׁוּ־לִי֙ אֵ֣שֶׁת בַּעֲלַת־א֔וֹב וְאֵלְכָ֥ה אֵלֶ֖יהָ וְאֶדְרְשָׁה־בָּ֑הּ וַיֹּאמְר֤וּ עֲבָדָיו֙ אֵלָ֔יו הִנֵּ֛ה אֵ֥שֶׁת בַּֽעֲלַת־א֖וֹב בְּעֵ֥ין דּֽוֹר׃
Then said Saul unto his servants: ‘Seek me a woman that divineth by a ghost, that I may go to her, and inquire of her.’ And his servants said to him: ‘Behold, there is a woman that divineth by a ghost at En-dor.’
Read Kabbalistic (mystical) interpretations of I Samuel 28:7: Zohar and classical Jewish mystical sources, free online.