1 Chronicles 10:13-14

So Saul died for his trespass against the Lord [in sparing Amalek], for his unfaithfulness in not keeping God's word, and also for consulting [a medium with] a spirit of the dead to inquire pleadingly of it, And inquired not so of the Lord [in earnest penitence]. Therefore the Lord slew him and turned the kingdom over to David son of Jesse. [I Sam. 28:6.]