The entire Israelite community left the Wilderness of Sin, moving from one place to the next according to the Lord's command. They camped at Rephidim, but there was no water for the people to drink.
References for Exodus 17:1
So the people complained to Moses: "Give us water to drink." "Why are you complaining to me?" Moses replied to them. "Why are you testing the Lord?"
But the people thirsted there for water, and grumbled against Moses. They said, "Why did you ever bring us out of Egypt to kill us and our children and our livestock with thirst?"
Then Moses cried out to the Lord, "What should I do with these people? In a little while they will stone me!"
The Lord answered Moses, "Go on ahead of the people and take some of the elders of Israel with you. Take the rod you struck the Nile with in your hand and go.
I am going to stand there in front of you on the rock at Horeb; when you hit the rock, water will come out of it and the people will drink." Moses did this in the sight of the elders of Israel.
He named the place Massah and Meribah because the Israelites complained, and because they tested the Lord, saying, "Is the Lord among us or not?"
References for Exodus 17:7