John Wesley on 1 Samuel 16:11

Keepeth sheep - And consequently is the most unfit of all my sons for that high employment. Either therefore he did not understand David's wisdom and valour, or he judged him unfit, by reason of his mean education. And God so ordered it by his providence, that David's choice might plainly appear to be God's work, and not Samuel's, or Jesse's. David signifies beloved: a fit name for so eminent a type of the Beloved Son. It is supposed, David was now about twenty years old. If so, his troubles by Saul lasted near ten years: for he was thirty years old when Saul died. Samuel having done this went to Ramah. He retired to die in peace, since his eyes had seen the salvation, even the sceptre brought into the tribe of Judah.