Exodus 15:22-24

The Waters of Marah and Elim 22Then Moses led Israel from the Red Sea and they went into the Desert of Shur. For three days they traveled in the desert without finding water. 23When they came to Marah, they could not drink its water because it was bitter. (That is why the place is called Marah. Marah means bitter. )

24So the people grumbled against Moses, saying, “What are we to drink?”