What do you do, when out following your normal day's routine, this crazy-popular prophet walks up and tells you you're going to be the king of Israel? Not just tells you...but annoints you in the name of the Lord to be the ruler of God's chosen people?
It would be a heady thing, frankly, so I don't fault Saul for hiding behind luggage prior to Samuel's introduction of him as Israel's new king. Because for him, his job was going to start immediately. Within five weeks of the initial annointing, Saul was off fighting Ammonites.
David, on the other hand, merely returned to his sheep (1 Samuel 16:19). I know I'd not be so patient or humble as to do that. I'd begin questioning God on what I should be doing now, or I'd look around for problems to fix, as Moses prematurely did. Perhaps I'd try tagging after Samuel, or at least pester my father to give me more responsibility amongst the family ventures. Yet David didn't: after Samuel annoints him, he went back to his sheep.
Could we be satisfied with that? Has God given a word of promise in your life, causing you immediately began expecting or trying to make happen? Because I'm exactly like that. If God says something, I expect it will happen, at the latest, next week. And if doesn't, I think perhaps I missed God and therefore strive to make the promise manifest myself.
I think David's story is a wonderful example for Christians of my bent. Even when David finds himself in the palace playing his harp to Saul, or in a cave with the indisposed king before him...he never saw those as opportunities to make God's promise happen for himself. He knew doing so would not only gain his ends deceitfully, but would also interfere with God's plan and perhaps even remove the blessing off his reign.
I wait for the Lord, my soul waits, and in his word, I put my hope. Psalm 130:5, NIV