Exodus 15:23

15:23 When they came to Marah, they couldn't drink from the waters of Marah, for they were bitter. Therefore the name of it was called Marah.
-World English Bible

Other Translation

15:23 And when they came to Marah, they could not drink of the waters of Marah, for they [were] bitter: therefore the name of it was called Marah.
-King James Version