Exodus 17:3, 6

But tormented by thirst, they continued to argue with Moses. “Why did you bring us out of Egypt? Are you trying to kill us, our children, and our livestock with thirst?”

I will stand before you on the rock at Mount Sinai. Strike the rock, and water will come gushing out. Then the people will be able to drink.” So Moses struck the rock as he was told, and water gushed out as the elders looked on.