1st Samuel 17:54

51 and David runneth and standeth over the Philistine, and taketh his sword, and draweth it out of its sheath, and putteth him to death, and cutteth off with it his head; and the Philistines see that their hero [is] dead, and flee.

52 And the men of Israel rise -- also Judah -- and shout, and pursue the Philistines till thou enter the valley, and unto the gates of Ekron, and the wounded of the Philistines fall in the way of Shaaraim, even unto Gath, and unto Ekron,

53 and the sons of Israel turn back from burning after the Philistines, and spoil their camps.

54 And David taketh the head of the Philistine, and bringeth it in to Jerusalem, and his weapons he hath put in his own tent.

55 And when Saul seeth David going out to meet the Philistine, he hath said unto Abner, head of the host, `Whose son [is] this -- the youth, Abner?` and Abner saith, `Thy soul liveth, O king, I have not known.`

56 And the king saith, `Ask thou whose son this [is] -- the young man.`

57 And when David turneth back from smiting the Philistine, then Abner taketh him and bringeth him in before Saul, and the head of the Philistine in his hand;