When the Israelites returned from chasing the Philistines, they plundered their camp.
David took the Philistine’s head and brought it to Jerusalem; he put the Philistine’s weapons in his own tent.
As Saul watched David going out to meet the Philistine, he said to Abner, commander of the army, “Abner, whose son is that young man?” Abner replied, “As surely as you live, Your Majesty, I don’t know.”
References for 1 Samuel 17:55
The king said, “Find out whose son this young man is.”
As soon as David returned from killing the Philistine, Abner took him and brought him before Saul, with David still holding the Philistine’s head.
“Whose son are you, young man?” Saul asked him. David said, “I am the son of your servant Jesse of Bethlehem.”
References for 1 Samuel 17:58