Charles H. Spurgeon on Psalms 78:70

He chose David also his servant. It was an election of a sovereignly gracious kind, and it operated practically by making the chosen man a willing servant of the Lord. He was not chosen because he was a servant, but in order that he might be so. David always esteemed it to be a high honour that he was both elect of God, and a servant of God. And took him from the sheepfolds. A shepherd of sheep he had been, and this was a fit school for a shepherd of men. Lowliness of occupation will debar no man from such honours as the Lord's election confers, the Lord seeth not as man seeth. He delights to bless those who are of low estate.