The chapter answers twice and the two answers are not identical. One verse credits the sling. The next has David standing over him with the giant’s own sword, finishing it and taking his head.
The throw itself stops at falling
And David put his hand in his bag, and took thence a stone, and slang it, and smote the Philistine in his forehead, that the stone sunk into his forehead; and he fell upon his face to the earth.
1 Samuel 17:49 (KJV)
The stone sinks in and the man goes down. Read only that verse and nobody has died yet, because it reports a wound and a fall and stops there.
The next verse says he killed him
So David prevailed over the Philistine with a sling and with a stone, and smote the Philistine, and slew him; but there was no sword in the hand of David.
1 Samuel 17:50 (KJV)
Slew him, with a sling and a stone, and the writer adds the clause everybody remembers. There was no sword in the hand of David.
That clause is doing something specific. It is not saying no sword was used in the episode, because the next verse has one, but that when the Philistine went down, the shepherd standing over him was unarmed by the standards of anybody watching.
He kills him a second time
Therefore David ran, and stood upon the Philistine, and took his sword, and drew it out of the sheath thereof, and slew him, and cut off his head therewith. And when the Philistines saw their champion was dead, they fled.
1 Samuel 17:51 (KJV)
Slew him, a second time, in consecutive verses. The Hebrew uses the same root in both, in two different forms, and the second form has a job of its own. Brown-Driver-Briggs adds one word to it that the first form does not have: dispatch.
First Samuel shows you the difference at 14:13. Jonathan climbs up on his hands and feet, the Philistines fall in front of him, and his armourbearer comes behind him doing this second thing, in exactly this form of the verb. One man knocks them down and the other finishes them. Judges has Abimelech, skull crushed by a millstone, asking his own armourbearer for it, and the Amalekite in 2 Samuel 1 claims he did it to Saul on Gilboa.
And notice what the Philistine army reacts to. David cuts the head off, and then they run.
The shorter Greek text does not have verse fifty
One detail changes what the difficulty is.
The Greek of 1 Samuel 17 in Codex Vaticanus is a much shorter chapter than the Hebrew. Twenty verses are missing from the middle of it and four from the end, and verse fifty is one of the ones it does not have. In the Greek, the stone goes in through the helmet and the man falls, and then David takes the sword and kills him. The verse that credits the sling with the killing is simply absent.
The two statements therefore sit together in the Hebrew, while that Greek text carries only one of them. Other Greek manuscripts have the missing verses, brought in later from the Hebrew. Nobody needs to choose, but it is worth knowing that the tradition has carried the chapter in more than one length.
The head is the thing he announced and the thing he carried
Before any of it, in his speech across the valley, David tells Goliath exactly what he intends. I will smite thee, and take thine head from thee.
Afterwards he takes the head to Jerusalem and puts the armour in his tent. When Abner brings him to Saul he is still holding it. And the women who come out singing do not mention a sling or a stone at all, only a count: Saul hath slain his thousands, and David his ten thousands.
The sword itself has a later life. Years on, running from Saul, David arrives at Nob and asks the priest for a weapon, and is told there is one wrapped in a cloth behind the ephod: the sword of Goliath the Philistine, whom thou slewest in the valley of Elah. David takes it back.
The ending I never told
The story I have told is the one about the small thing beating the large one, and that story is in the chapter and it is true. What I left out every time was the last third, which is a young man standing on a body, sawing, and then walking to the king with a head in his hand.
Leaving it out makes a fable of it. Keeping it in makes it a war, which the chapter says it was. Tradition made a fable of Mary Magdalene too, and for the same reason: it preaches better.
One more difficulty, named rather than hidden
A reader who goes looking will meet this, so it is better met here.
In 2 Samuel 21:19 the King James reads that Elhanan slew the brother of Goliath the Gittite, and the words the brother of are supplied by the translators, printed in italics because there is nothing behind them in the Hebrew. First Chronicles 20:5 tells the same event and there the word brother is genuinely present, with Lahmi named as the victim.
Careful readers have worked on that pair for centuries without agreeing, and I can’t settle it here. It is a different question from the one this article asks, which is what 1 Samuel 17 says happened, and on that the chapter is clear enough about both the stone and the sword.
Hold both halves
A stone that fells a man, a summary verse that credits the sling, a sword that finishes him, and a head carried off the field.
First Samuel puts two accounts of one death in consecutive verses and lets the reader carry both.
Verse forty-seven says what the fight was about, before a stone is thrown. The LORD saveth not with sword and spear, David tells them, for the battle is the LORD’s. He says it out loud to the whole field, before he has done a single thing, and that sentence survives the beheading. The fable does not survive it, and the fable is the half most people take home.