55As soon as Saul saw David go out against the Philistine, he said to Abner, the commander of the army, “Abner, whose son is this youth?” And Abner said, “As your soul lives, O king, I do not know.”
Abner makes use of a common oath formula to underscore his inability to answer the question.1
55 As soon as Saul saw David go out against the Philistine, he said to Abner, the commander of the army, “Abner, whose son is this youth?” And Abner said, “As your soul lives, O king, I do not know.”