Judges 20:16

From all these troops [were] seven hundred well-trained men {who were left-handed}; each one could sling with a stone at a hair and not miss.

Judges 3:15

And the {Israelites} cried out to Yahweh, and Yahweh raised up for them a deliverer, Ehud son of Gera, a Benjaminite and {a left-handed man}. And the {Israelites} sent a tribute to Eglon king of Moab {through him}.

1 Chronicles 12:2

[They were] armed with [the] bow, [able to shoot] right-handed or left-handed, [slinging] stones or [shooting] arrows with the bow; [they were] kinsmen of Saul from Benjamin.

1 Samuel 17:40

Then he took his staff in his hand, picked out for himself five smooth stones from the wadi, and he put them in his shepherd's bag, in the pouch. And with his sling in his hand, he approached the Philistine.

1 Samuel 17:49-50

Then David put his hand into the bag and took a stone from it and slung [it]. He struck the Philistine on his forehead, and the stone sank into his forehead, and he fell on his face to the ground.

1 Samuel 25:29

Should a man arise to pursue you and to seek your life, may the life of my lord be wrapped in the pouch of the living with Yahweh your God. But as for the life of your enemy, he will sling it from within the pocket of the sling!

2 Chronicles 26:14

And Uzziah prepared small shields, spears, helmets, breastplates, bows, and slingstones for the whole army.

Treasury of Scripture Knowledge

Summary

Among all this people there were seven hundred chosen men lefthanded; every one could sling stones at an hair breadth, and not miss.

Bible References

Left-handed

Judges 3:15
And the {Israelites} cried out to Yahweh, and Yahweh raised up for them a deliverer, Ehud son of Gera, a Benjaminite and {a left-handed man}. And the {Israelites} sent a tribute to Eglon king of Moab {through him}.
1 Chronicles 12:2
[They were] armed with [the] bow, [able to shoot] right-handed or left-handed, [slinging] stones or [shooting] arrows with the bow; [they were] kinsmen of Saul from Benjamin.

Sling stones

1 Samuel 17:40
Then he took his staff in his hand, picked out for himself five smooth stones from the wadi, and he put them in his shepherd's bag, in the pouch. And with his sling in his hand, he approached the Philistine.
1 Samuel 25:29
Should a man arise to pursue you and to seek your life, may the life of my lord be wrapped in the pouch of the living with Yahweh your God. But as for the life of your enemy, he will sling it from within the pocket of the sling!
2 Chronicles 26:14
And Uzziah prepared small shields, spears, helmets, breastplates, bows, and slingstones for the whole army.