1 Samuel 17:40
"And he took his staff in his hand, and chose him five smooth stones out of the brook, and put them in a shepherd’s bag which he had, even in a scrip; and his sling was in his hand: and he drew near to the Philistine."
Cross References (ranked by relevance)
Judges 20:16
Among all this people there were seven hundred chosen men lefthanded; every one could sling stones at an hair breadth, and not miss.
Matthew 10:10
Nor scrip for your journey, neither two coats, neither shoes, nor yet staves: for the workman is worthy of his meat.
Judges 3:31
And after him was Shamgar the son of Anath, which slew of the Philistines six hundred men with an ox goad: and he also delivered Israel.