It is not clear exactly how old David was at this point in time. When Saul referred to him as a boy, he was not drawing attention to his youth but rather his lack of military training and experience.1 Likewise, when David objected to marrying Saul’s daughter Merab, he did not mention his age either (see 1 Samuel 18:18).
33 Saül dit à David: Tu ne peux pas aller te battre avec ce Philistin, car tu es un enfant, et il est un homme de guerre dès sa jeunesse.