Moses named that place Meribah and Massah, because this was the place that the Israelites turned against him and tested the Lord. The people wanted to know if the Lord was with them or not.
So they turned against Moses and started arguing with him. They said, “Give us water to drink.” Moses said to them, “Why have you turned against me? Why are you testing the Lord?”
Moses said this about Levi: “Levi is your true follower. He keeps the Urim and Thummim. At Massah you tested the people of Levi. At the waters of Meribah, you challenged them.