Saul fought against the Philistines in 1 Samuel 31:
There is another account in 2 Samuel 1:
Who Killed Saul?
Possibility #1: Saul killed himself and the young Amalekite lied.
Possibility #2: Saul tried to kill himself. The armor-bearer presumed Saul was dead and killed himself. Finally, the Amalekite finished Saul at his request.
On balance, I'd go with Saul killing himself. As far as the narrator was concerned, there was no contradiction. I put a bit more weight on the narrator's perspective than on that of the young Amalekite.
According to this account, Saul killed himself. There was a witness: the armor-bearer. The narrator agreed with this account.3The battle pressed hard against Saul, and the archers found him, and he was badly wounded by the archers. 4Then Saul said to his armor-bearer, “Draw your sword, and thrust me through with it, lest these uncircumcised come and thrust me through, and mistreat me.” But his armor-bearer would not, for he feared greatly. Therefore Saul took his own sword and fell upon it. 5 And when his armor-bearer saw that Saul was dead, he also fell upon his sword and died with him. 6 Thus Saul died, and his three sons, and his armor-bearer, and all his men, on the same day together.
There is another account in 2 Samuel 1:
According to the above, a young Amalekite killed Saul. The narrator reported his story without affirming it.5Then David said to the young man who told him, “How do you know that Saul and his son Jonathan are dead?” 6 And the young man who told him said, “By chance I happened to be on Mount Gilboa, and there was Saul leaning on his spear, and behold, the chariots and the horsemen were close upon him. 7And when he looked behind him, he saw me, and called to me. And I answered, ‘Here I am.’ 8And he said to me, ‘Who are you?’ I answered him, ‘I am an Amalekite.’ 9 And he said to me, ‘Stand beside me and kill me, for anguish has seized me, and yet my life still lingers.’ 10 So I stood beside him and killed him, because I was sure that he could not live after he had fallen. And I took the crown that was on his head and the armlet that was on his arm, and I have brought them here to my lord.”
Who Killed Saul?
Possibility #1: Saul killed himself and the young Amalekite lied.
Possibility #2: Saul tried to kill himself. The armor-bearer presumed Saul was dead and killed himself. Finally, the Amalekite finished Saul at his request.
On balance, I'd go with Saul killing himself. As far as the narrator was concerned, there was no contradiction. I put a bit more weight on the narrator's perspective than on that of the young Amalekite.