1 Chronicles 10:13

13 So Saul died because of his unfaithfulness to the LORD: He did not obey the word of the LORD. He asked a medium to request information [from a dead person].

1 Chronicles 10:13 Meaning and Commentary

1 Chronicles 10:13

So Saul died for his transgression
(See Gill on 1 Samuel 31:13) A violent and dishonourable death, which was suffered on account of the sins he was guilty of:

one was, which he committed against the Lord, even against the word of
the Lord, which he kept not;
both in not staying for Samuel the time appointed, and by sparing the Amalekites whom he was bid to destroy, ( 1 Samuel 13:13 1 Samuel 13:14 ) ( 1 Samuel 15:3 1 Samuel 15:9 )

and also for asking counsel of one that had a familiar spirit, to
inquire of it;
what he should do with respect to engaging in battle with the Philistines, ( 1 Samuel 28:8 1 Samuel 28:15 ) which to do was contrary to an express command of God, ( Leviticus 19:31 ) .

1 Chronicles 10:13 In-Context

11 When all the people of Jabesh Gilead heard about everything the Philistines had done to Saul,

12 all the fighting men came and took away the dead bodies of Saul and his sons and brought them to Jabesh. They buried the bones under the oak tree in Jabesh. Then they fasted seven days.

13 So Saul died because of his unfaithfulness to the LORD: He did not obey the word of the LORD. He asked a medium to request information [from a dead person].

14 He didn't request information from the LORD. So the LORD killed him and turned the kingship over to David, Jesse's son.