What does 1 Samuel 17:40 mean?
David has offered to fight the imposing giant Goliath (1 Samuel 17:1–10) on Israel's behalf, confident that God will bring the victory (1 Samuel 17:31–37). King Saul has agreed and has offered his armor (1 Samuel 17:38). But David has not trained with the armor and chooses against wearing it (1 Samuel 17:39). Instead, David goes to battle as a shepherd. Staff in hand, David gathers ammunition for his weapon—a sling.Despite how David's sling is often portrayed, this was not a "slingshot" or a small piece of cloth used to fling pebbles. Though sometimes called a shepherd's weapon, it was also well-accepted as a weapon of war (Judges 20:16; 1 Chronicles 12:2). Men armed with slings were depicted in ancient battle murals.
The sling consisted of a leather pouch in the middle of a long cord. Stones were placed in the pouch, and both ends of the cord were held so the stone could be swung with great force. Releasing one end of the cord—the other usually tied to the wrist—would release the rock. Firing a sling with power could produce a sharp cracking sound, exactly like that of a bullwhip. These projectiles were usually the size of a large coin but could be as big as a man's fist. In the right hands, these weapons were accurate and deadly to a hundred yards or ninety meters.
David approaches the battlefield where Goliath has been calling out his challenges in defiance of the armies of Israel (1 Samuel 17:16, 23). He stops on the way to pick up five smooth stones for his sling from the bed of the brook that runs through the Valley of Elah (1 Samuel 17:1–3). These would have been the best for accuracy. David approaches Goliath, without protective gear armed with only a loaded sling. Saul, who already knows David (1 Samuel 16:18–22), is impressed enough to ask for more details about the young man (1 Samuel 17:55)