Exposition of the Old and New Testament, by John Gill, [1746-63], at sacred-texts.com
This part, Ch1 10:1 which gives an account of the last battle of Saul with the Philistines, and of his death and burial, is the same with Sa1 31:1 see the notes there; the cause of his death follows in Ch1 10:13
See Gill on Sa1 31:1. So Saul died for his transgression,.... See Gill on Sa1 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, Sa1 13:13.
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, Sa1 28:8 which to do was contrary to an express command of God, Lev 19:31.
And inquired not of the Lord,.... For though he did inquire in some sense in an external, careless, and hypocritical manner, yet not done seriously, sincerely, and heartily, nor with constancy; it was accounted as if he inquired not at all, Sa1 28:6 the Targum adds another reason of his death, because he killed the priests of Nob; but that is not in the text:
therefore he slew him; or suffered him to be slain:
and turned the kingdom unto David the son of Jesse; translated the kingdom of Israel out of Saul's family, upon his death, into Jesse's, even unto David; for the sake of which observation this short account is given of the last end of Saul.