1 Samuel 16 — We immediately see the superiority of David over Saul. God calls David a king right off the bat (v. 1) while he only called Saul a prince (1 Sam. 9:16; 10:1; 13:14). Verse 7 is an obvious dig at Saul was was head and shoulders above all the men of Israel (1 Sam. 9:2; 10:23). It is surely significant that David is Jesse’s eighth son (vv. 10-11 cf. 17:12) since eight represents new beginnings or new birth. David is a new type of king; one after God’s own heart; and he represents a new Israel. We also notice that David was working when God called him (v. 11); we see this in the Gospels when Jesus calls his disciples. And like Saul (1 Sam. 9:2), David is handsome (v. 12), and I’ll suggest later that he was tall as well. I need to give some more thought to his being “ruddy.” Esau was said to be ruddy as well (Gen. 25:25) so I wonder if there’s some kind of connection between the two.
1 Samuel 17 — David is an obedient Israel who remembers what the LORD had done for him and has confident that he’ll do it again (v. 37). It is common to hear that David was a runt, the smallest of Jesse’s sons, but if this were the case then how could he fit into Saul’s armor (vv. 38-39)? Why would Saul even think to put it on him? In fact, we only read of David being the youngest or a youth (1 Sam. 16:11; 17:14, 33, 42, 55), never of him being short or small. So David is just like Saul in some respects, i.e., he’s tall and handsome; but he’s unlike Saul in the most important respect: God chose him!
Why does David grab five smooth stones (v. 40)? Depending on how one understands the textual tradition it is possible to assert that Goliath had four brothers: Ishbibenob, Saph, Lahmi, and the unnamed giant with six fingers on each hand and six toes on each foot (2 Sam. 21:15-22). So perhaps David believed that after he killed Goliath he’d have to kill his brothers. But five is the number of grace (and it also reminds us of God’s instruction: Pentateuch = 5 books; Torah = instruction). Why smooth stones? Sure, a smooth stone is more aerodynamic and easier to sling than a jagged stone, but these were stones that had been eroded by the flowing water of the brook from which David grabbed them. The Spirit is a “river of living water” (John 7:38-39) eroding the jagged edges of the people of God. The five smooth stones gathered from the brook prefigure the eschatological Spirit of grace the LORD will pour out on the house of David when he seeks to destroy the nations that come against Jerusalem (Zech. 12:9-10).
David didn’t approach Goliath with weapons of war. Goliath was insulted that he came to him with sticks (v. 43) but David came in the name of the LORD of hosts (v. 45), knowing that the LORD gives victory in battle, not military might (vv. 46-47). Contrast this with Saul and Jonathan who had swords and spears while the people of Israel were armed with farming instruments (1 Sam. 13:22). This is another area in which David was a vast improvement on Saul; he had an unwavering faith in the LORD!
1 Samuel 18 — Saul charged David with bringing him a hundred Philistine foreskins because he didn’t think David could do it and that he’d die trying (v. 25) but David succeeded and brought him twice the price he asked (v. 27). The removal of foreskin is a sign of covenant with the LORD (Gen. 17:11) and David had no fear of or respect for uncircumcised Philistines (1 Sam. 17:26, 36) since he knew they had no covenant. Removing their foreskins postmortem makes a mockery of their lack of covenant. Too little, too late.