Exodus 17:3

17:3 But the people were very thirsty there for water, and they murmured against Moses and said, “Why in the world did you bring us up out of Egypt – to kill us and our children and our cattle with thirst?”

Exodus 17:6

17:6 I will be standing before you there on the rock in Horeb, and you will strike the rock, and water will come out of it so that the people may drink.” And Moses did so in plain view of the elders of Israel.