David said something that is really key in prevailing over our enemy. Saul wanted him to use his armor. David put it on, but it was too heavy and he couldn’t walk in it. In 1 Samuel 17:39 David said, “…I cannot walk in these, for I have not tested them…”
He knew that he had tested his sling. He recounted to Saul the things that the Lord did for him as a shepherd. Verse 36 says that he killed a lion and a bear, and, “…this uncircumcised Philistine will be like one of them…”
Here was his tried, tested, and proven way. Verse 40 says, “Then he took his staff in his hand, and he chose for himself five smooth stones from the book, and put them in a shepherd’s bag, in a pouch which he had, and his sling was in his hand…” All rather by rote actions.
Do you recall the words to the hymn, “Tis So Sweet To Trust In Jesus” written by Louisa Stead? Verse 4 starts with, “I’m so glad I learned to trust Thee.” Why did she write those words? She watched both her husband and the little boy he was trying to save drown.
She had proven the Lord was faithful in her relationship with Him in the past. The chorus starts, “Jesus, Jesus, how I trust Him! How I’ve proved Him o’er and o’er.” She leaned on the truth about Him that was proven throughout her life. When the new need presented itself, she knew immediately where to turn.