Acts 13:2-3 - ”While they were worshiping the Lord and fasting, the Holy Spirit said, “Set apart for me Barnabas and Saul for the work to which I have called them.” So after they had fasted and prayed, they placed their hands on them and sent them off.”
“Paul and Barnabas appointed elders for them in each church and, with prayer and fasting, committed them to the Lord, in whom they had put their trust.” - Acts 14:23
1 Samuel 17:4-7 - “A champion named Goliath, who was from Gath, came out of the Philistine camp. He was over nine feet tall. He had a bronze helmet on his head and wore a coat of scale armor of bronze weighing five thousand shekels; on his legs he wore bronze greaves, and a bronze javelin was slung on his back. His spear shaft was like a weaver’s rod, and its iron point weighed six hundred shekels. His shield bearer went ahead of him…”
1 Samuel 17:40 – “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.”
When David was preparing to fight Goliath, he refused the fancy royal armor and weapons of Saul (1 Samuel 17:38-39). Instead, he ensured his victory by first kneeling alone at the brook and picking five smooth stones to use in his slingshot. This is a prophetic picture of how we need to use spiritual weapons to fight our battles with our own fleshly tendencies and attitudes. Just as the stones in the stream were smooth from the constant flow of water over them (and their smoothness made them effective in the sling), there are certain spiritual disciplines through which the Holy Spirit flows abundantly, and which are very effective in overcoming the internal obstacles to our faith. We call these the Means of Grace because they open a conduit for God’s grace to flow more abundantly into our lives.