Exodus 17: 1-6
Water From The Rock

Then all the congregation of the children of Israel set out on their journey from the Wilderness of Sin, according to the commandment of the Lord, and camped in Rephidim; but there was no water for the people to drink.
Therefore the people contended with Moses, and said, "Give us water, that we may drink." So Moses said to them, "Why do you contend with me? Why do you tempt the Lord?"
And the people thirsted there for water, and the people complained against Moses, and said, "Why is it you have brought us up out of Egypt, to kill us and our children and our livestock with thirst?"
So Moses cried out to the Lord, saying, "What shall I do with this people? They are almost ready to stone me!"
And the Lord said to Moses, "Go on before the people, and take with you some of the elders of Israel. Also take in your hand your rod with which you struck the river, and go.
Behold, I will stand before you there on the rock in Horeb; and you shall strike the rock, and water will come out of it, that the people may drink."
And Moses did so in the sight of the elders of Israel.