I Samuel 17:55

55 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."

55 And when Saul saw David going out against the Philistine, he said to Abner, the captain of the army, Abner, whose son is this young man? And Abner said, On your life, O king, I have no idea.