So Saul died for his unfaithfulness which he had committed against the LORD, because he did not keep the word of the LORD, and also because he consulted a medium for guidance.
1 Chronicles 10:13
Surrounding context
10:12 all the valiant men arose and took the body of Saul and the bodies of his sons; and they brought them to Jabesh, and buried their bones under the tamarisk tree at Jabesh, and fasted seven days.
10:13 So Saul died for his unfaithfulness which he had committed against the LORD, because he did not keep the word of the LORD, and also because he consulted a medium for guidance.
10:14 But he did not inquire of the LORD; therefore He killed him, and turned the kingdom over to David the son of Jesse.