Exodus 17:3, 6

But the people were thirsty for water there, and they grumbled against Moses. They said, “Why did you bring us up out of Egypt to make us and our children and livestock die of thirst?”

I will stand there before you by the rock at Horeb. Strike the rock, and water will come out of it for the people to drink.” So Moses did this in the sight of the elders of Israel.