Only fear Yahweh, and serve him in truth with all your heart; for consider how great things he has done for you.
So you do remember that he started out his career extremely early. As soon as he was weaned he was a public figure. He was there in the place of worship. The people who would gather for worship saw this little boy year by year as he grew and as he developed. They recognized that God's hand was upon this young man. He just sort of naturally grew into the position of leadership and judge over Israel.