1 Samuel 31:4...Saul took a sword, and fell upon it. 5 And when his armourbearer saw that Saul was dead, he fell likewise upon his sword, and died with him. 6 So Saul died, and his three sons, and his armourbearer, and all his men, that same day together.
The account is repeated in 1 Chronicles 10:4
1 Chronicles 10:4... So Saul took a sword, and fell upon it. 5 And when his armourbearer saw that Saul was dead, he fell likewise on the sword, and died. 6 So Saul died, and his three sons, and all his house died together.
What we are told in 1 Samuel 31:4 and 1 Chronicles 10:4 is narrative written by inspiration of God.
2 Timothy 3:16 All scripture is given by inspiration of God...
It is therefore a true record of the death of Saul.
What is recorded in 2 Samuel 1 is what the Amalekite said.
2 Samuel 1:6 And the young man that told him said, As I happened by chance upon mount Gilboa, behold, Saul leaned upon his spear; and, lo, the chariots and horsemen followed hard after him. 7 And when he looked behind him, he saw me, and called unto me. And I answered, Here am I. 8 And he said unto me, Who art thou? And I answered him, I am an Amalekite. 9 He said unto me again, Stand, I pray thee, upon me, and slay me: for anguish is come upon me, because my life is yet whole in me. 10 So I stood upon him, and slew him, because I was sure that he could not live after that he was fallen: and I took the crown that was upon his head, and the bracelet that was on his arm, and have brought them hither unto my lord.
As the Bible records twice what actually happened, it is reasonable to conclude that the Amalekite was telling lies in an attempt to extract a reward from David. David’s later comment indicates this:
2 Samuel 4:10 When one told me, saying, Behold, Saul is dead, thinking to have brought good tidings, I took hold of him, and slew him in Ziklag, who thought that I would have given him a reward for his tidings:
What the Amalekite was not aware of was that David could not condone the killing of Saul because Saul was anointed by Samuel (on God’s instruction) to be king over Israel. David on two occasions had refused to kill Saul because he was ‘the LORD’S anointed’.
1 Samuel 24:6... he said unto his men, The LORD forbid that I should do this thing unto my master, the LORD’S anointed, to stretch forth mine hand against him, seeing he is the anointed of the LORD.
1 Samuel 26:9... David said to Abishai, Destroy him not: for who can stretch forth his hand against the LORD’S anointed, and be guiltless?
In the narrative Saul’s armourbearer was afraid to kill Saul; we might suppose for the same reason.
1 Samuel 31:4 Then said Saul unto his armourbearer, Draw thy sword, and thrust me through therewith; lest these uncircumcised come and thrust me through, and abuse me. But his armourbearer would not; for he was sore afraid...
David says to the Amalekite:
2 Samuel 1:14... How wast thou not afraid to stretch forth thine hand to destroy the LORD’S anointed?
By telling lies in the hope of gaining a reward the Amalekite brought about his own death. Even though he was not actually guilty of killing Saul, in claiming that he had done, he left David with no option but to condemn him to death.
I hope you have found this helpful.
God bless you,