It appears as if Jesse did not think that his youngest son would be an appropriate candidate for service to the Lord.1 Because he was the youngest and the smallest, he thought it best to leave him tending the sheep so that the older boys could spend time with Samuel. Interestingly, the Lord’s choice of Jesse's youngest is similar to his earlier choice of Jacob (Genesis 25:23) and Ephraim (Genesis 48:8–22).2
11 Puis Samuel dit à Isaï: Sont-ce là tous tes fils? Et il répondit: Il reste encore le plus jeune, mais il fait paître les brebis. Alors Samuel dit à Isaï: Envoie-le chercher, car nous ne nous placerons pas avant qu'il ne soit venu ici.