The JPS Torah Commentary, Nahum Sarna (p. 136)
The belief in and practice of magic was universal in the ancient world...The attempt to activate and manipulate to one's advantage the mysterious supernatural forces inherent in this [polytheistic] realm constituted the essence of magic. Elaborate techniques were developed to this end, and magic became an indispensable ingredient of religion. Apart from the practical and verbal procedures, and the personnel who specialized in them, there were also individuals who were thought to possess inherent mystical powers capable of exploiting the occult properties of the extramundane realm....Biblical monotheism, with its uncompromising insistence of the absolute omnipotence of one universal, sovereign, creator God, was totally irreconcilable with the underlying postulates of magic. The religion of Israel ruthlessly and relentlessly fought to extirpate such beliefs and practices.
כִּ֤י אַתָּה֙ בָּ֣א אֶל־הָאָ֔רֶץ אֲשֶׁר־ה' אֱלֹהֶ֖יךָ נֹתֵ֣ן לָ֑ךְ לֹֽא־תִלְמַ֣ד לַעֲשׂ֔וֹת כְּתוֹעֲבֹ֖ת הַגּוֹיִ֥ם הָהֵֽם׃ לֹֽא־יִמָּצֵ֣א בְךָ֔ מַעֲבִ֥יר בְּנֽוֹ־וּבִתּ֖וֹ בָּאֵ֑שׁ קֹסֵ֣ם קְסָמִ֔ים מְעוֹנֵ֥ן וּמְנַחֵ֖שׁ וּמְכַשֵּֽׁף׃ (יא) וְחֹבֵ֖ר חָ֑בֶר וְשֹׁאֵ֥ל אוֹב֙ וְיִדְּעֹנִ֔י וְדֹרֵ֖שׁ אֶל־הַמֵּתִֽים׃ כִּֽי־תוֹעֲבַ֥ת ה' כָּל־עֹ֣שֵׂה אֵ֑לֶּה וּבִגְלַל֙ הַתּוֹעֵבֹ֣ת הָאֵ֔לֶּה ה' אֱלֹהֶ֔יךָ מוֹרִ֥ישׁ אוֹתָ֖ם מִפָּנֶֽיךָ׃ תָּמִ֣ים תִּֽהְיֶ֔ה עִ֖ם ה' אֱלֹהֶֽיךָ׃
When you enter the land which the Eternal your God gives you, you shall not learn to do like the abominations of those nations. There shall not be found among you any one that passes their son or their daughter through the fire, one that divines divination, a soothsayer, or an enchanter, or a sorcerer, or a charmer, or one that consults a ghost or a familiar spirit, or a necromancer. For whosoever does these things is an abomination to the Eternal; and because of these abominations the Eternal your God is driving them out from before you. You shall be whole with the Eternal your God.
תמים תהיה עם ה' אלהיך. התהלך עמו בתמימות ותצפה לו ולא תחקור אחר העתידות, אלא כל מה שיבא עליך קבל בתמימות ואז תהיה עמו ולחלקו:
"You shall be whole with the Eternal your God." Walk with God with integrity and look only to God. Do not investigate the future; rather, all that comes upon you, accept with integrity - and thus you will be with God and God's portion.
וַיִּשְׁאַ֤ל שָׁאוּל֙ בַּֽה' וְלֹ֥א עָנָ֖הוּ ה' גַּ֧ם בַּחֲלֹמ֛וֹת גַּ֥ם בָּאוּרִ֖ים גַּ֥ם בַּנְּבִיאִֽם׃ (ז) וַיֹּ֨אמֶר שָׁא֜וּל לַעֲבָדָ֗יו בַּקְּשׁוּ־לִי֙ אֵ֣שֶׁת בַּעֲלַת־א֔וֹב וְאֵלְכָ֥ה אֵלֶ֖יהָ וְאֶדְרְשָׁה־בָּ֑הּ וַיֹּאמְר֤וּ עֲבָדָיו֙ אֵלָ֔יו הִנֵּ֛ה אֵ֥שֶׁת בַּֽעֲלַת־א֖וֹב בְּעֵ֥ין דּֽוֹר׃
(6) And when Saul asked the Eternal, the Eternal did not answered him, neither by dreams, nor by Urim, nor by prophets. Then said Saul to his servants: ‘Seek out for me a ghost-wife , that I will go to, and inquire of her.’ And his servants said to him: ‘Look, there is a ghost-wife at En-dor.’