1 Chronicles 10:11-13

10:11 When all the residents of Jabesh Gilead heard about everything the Philistines had done to Saul, 10:12 all the warriors went and recovered the bodies of Saul and his sons and brought them to Jabesh. They buried their remains under the oak tree in Jabesh and fasted for seven days.

10:13 So Saul died because he was unfaithful to the Lord and did not obey the Lord’s instructions; he even tried to conjure up underworld spirits.