1 Samuel 28:3-25
Now Samuel was dead, and all Israel had lamented him, and buried him in Ramah, even in his own city. And Saul had put away those that had familiar spirits, and the wizards, out of the land. 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 inquired of the LORD, the LORD answered him not, neither by dreams, nor by Urim, nor by prophets. read more
1 Chronicles 10:13
So Saul died for his transgression which he committed against the LORD, even against the word of the LORD, which he kept not, and also for asking counsel of one that had a familiar spirit, to inquire of it;
1 Samuel 15:23
For rebellion is as the sin of witchcraft, and stubbornness is as iniquity and idolatry. Because thou hast rejected the word of the LORD, he hath also rejected thee from being king.