Numbers 21:17-18

Spring up Hebrew, ascend; that is, let thy waters, which now lie hid below in the earth, ascend for our use. It is either a prediction that it should spring up, or a prayer that it might. With their staves Probably as Moses smote the rock with his rod, so they struck the earth with their staves, as a sign that God would cause the water to flow out of the earth where they smote it, as he did before out of the rock. Or, perhaps, they made holes with their staves in the sandy ground, and God caused the water immediately to spring up.