1 Samuel 17:51-55

Then David ran and stood over the Philistine, and took his sword and drew it out of its sheath and finished him, and cut off his head with it. When the Philistines saw that their champion was dead, they fled.

Then the men of Israel and Judah rose up and shouted, and they pursued the Philistines as far as the valley, and to the gates of Ekron. And the Philistine dead lay along the way to Shaaraim, even to Gath and Ekron.

Then the sons of Israel returned from their close pursuit of the Philistines, and plundered their camps.

And David took the Philistine’s head and brought it to Jerusalem, but he put his weapons in his tent.

Now when Saul had seen David going out against the Philistine, he said to Abner the commander of the army, “Abner, whose son is this young man?” And Abner said, “By your life, O king, I do not know.”