Ewald Schmidt 

Then Saul dressed David in his own tunic. He put a coat of armour on him and a bronze helmet on his head. David fastened on his sword over the tunic and tried walking around, because he was not used to them. “I cannot go in these,” he said to Saul, “because I am not used to them.” So he took them off. Then he took his staff in his hand, chose five smooth stones from the stream, put them in the pouch of his shepherd’s bag and, with his sling in his hand, approached the Philistine.” 1 Samuel 17:38-40 NIV
It came to King Saul’s ears that his young musician was upset over Goliath’s words, and the fear of the army of Israel to do something about it. Saul ordered David to come and explain himself. In 1 Samuel 17:32, David reminds Saul that one should not lose heart over a giant, he would go and fight Goliath. Saul tells him that he is still a child, and Goliath is a mighty warrior since his youth. David looks back over his own experience of God’s protection, and remembers the lion and the bear trying to catch his father’s lambs. With some youthful exuberance, he tells Saul how he caught the lion and the bear by the beard, and struck these to death. David has the youthful courage and belief that the giant will go down the same way with God’s help (1 Samuel 17:36).
King Saul would have had the best weapons available at his disposal. He offers it to David. But David can barely move in Saul’s armour. We should remember that Saul was huge himself, he was physically and morally the right person to do this job. But he did not.
David declines Saul’s weapons. He takes up the weapons with which he is familiar, his shepherd’s staff, and his slingshot. He picked up five smooth stones from the creek. Then he was ready to approach the giant for their confrontation. We learn a valuable lesson in this chapter. When Paul talks about the armour of the Spirit in Ephesians 6:10-20, he reminds us that our battle is not against humans, against flesh and blood. Our weapons are also not of this world. We use the weapons of God in the battle of life. The weapons that David chose came from his experience, where he lived and worked with God’s protection. With faith in his heart, and the weapons he was familiar with, he was ready to approach his giant.
Prayer: Lord, thank you that you have equipped me with the armour of God. No giant shall stand in my way when I am on your mission in life! Amen