Wonder not that David was so suddenly advanced, from a poor contemptible shepherd, to so great reputation; for these were the effects of that Spirit of the Lord, which he received when he was anointed; though some would hence infer, that the things related in this chapter happened after the history of 1Sa 17, though it be placed before, such transpositions being not unusual in historical relations. The Lord is with him, i.e. directs and prospers all his undertakings.
Related Commentaries of 1 Samuel 16:18
1 Samuel 16:18
18 Then answered one of the servants, and said, Behold, I have seen a son of Jesse the Bethlehemite, that is cunning in playing, and a mighty valiant man, and a man of war, and prudent in matters,f and a comely person, and the LORD is with him.