When Saul saw David go forth against the Philistine, he said to Abner, the captain of the host, Abner, whose son is this youth? Abner said, As your soul lives, O king, I can't tell.
The stone that hit Goliath in the forehead evidently only knocked him out. David then approached the fallen giant, slew him with his own sword, and cut off his head. [Note: Baldwin, p. 128; Ariella Deem, "’And the Stone Sank Into His Forehead’: A Note on 1 Samuel xvii 49," Vetus Testamentum 28:3 (1978):350.] 1 Samuel 17:50 seems to be a summary of the whole encounter. 1 Samuel 17:49; 1 Samuel 17:51 apparently describe what happened blow by blow. By cutting off Goliath’s head David completed the execution of the giant and demonstrated to everyone present that he really was dead. Like the image of Dagon, that had previously fallen before the ark and had its head broken off (1 Samuel 5:4), so Dagon’s champion now suffered the same fate.